Karl’s Xiao Long Bao (aka XLB or Soup Dumplings)

Xiao long bao (小笼包, literally “little-basket bun”) is the hot new food in San Jose this year—several restaurants have opened or recently started specializing in these Asian delights. XLBs—for short—is a kind of dim sum that falls somewhere between a steamed bun (baozi) and a dumpling (jiaozi). Both of these are usually filled with meat and/or vegetables. Boazi tend to be dry both inside and out. Jiaozi may be moister inside, but are frequently put into a soup. With xiao long bao the hot savory soup is actually already inside the bun with the filling. Son-in-law Chris has challenged me to learn to make this uniquely Shanghai dish.

Note: Although the Taiwanese claim it as their own.

Note: Of particular interest—to anyone wishing to make Chinese dumplings—will be the discussion of the science of dumpling dough.

Note: This recipes for Xiao Long Bao is very complex, basically an article—10 pages—rather than a post. Jan and daughter Miriam suggest that blog readers generally do not like such long posts. This recipe is actually four recipes in one, so I will post each of these separately with an introductory and concluding post. For my readers who do not mind reading a long post, I will also post the entire article separately.

Karl’s Xiao Long Bao (Introduction) Start of the five short posts

This turned out to be a very complicated and time consuming recipe. It is not for the faint of heart, but the payoff is well worth it—it produces a spectacularly tasty treat. One way of making the production of them more enjoyable is to prepare all of the ingredients up to the point where you are ready to roll out and fill the wrappers. You then invite a group of friends to help you roll, fill, and eat the dumplings. A couple of glasses of wine, some good conversation, and you have a party.

I examined a lot of recipes online for clues to both ingredients and techniques for this dish. there was very little agreement on any aspect of making them.  The basic recipe has four major parts—the soup, the filling, the wrappers, and the dipping sauce.

The Soup 

Since it is impossible to pour hot soup into a raw piece of dough, there had to be a trick to making these soup filled buns. The secret is to turn the soup into aspic—a meat jelly. Many of the “quick” recipes call for using powdered gelatin. The more traditional recipes call for boiling pig skin for hours to break down its collagen to make the gelatin.  If you are using this technique, it is advisable to begin making the soup the day before you plan to make these dumplings.

Note: A couple of the recipes called for blending the skin into a slurry and either leaving it in or straining the broth after blending. I do not recommend doing this.

The simplest XLB soup recipes, I found, called for simply boiling the skin with some green onions and ginger. This type of recipe depends mostly upon the ingredients in the filling to give the soup most of its flavor. While there is nothing inherently wrong with this, I wanted something more.

Other recipes use pork belly—with the skin still on—or a combination of pork cuts, including pig’s feet. These recipes produce a soup with an enhanced pork flavor and would still pick up some additional flavoring from the savory liquid shed by the filling ingredients. While better than the simplest recipes, the soup would still be fairly one dimensional.

The most savory soups included chicken bones and Chinese ham—as well as the pig skin. This technique produces a more complex flavorful broth. Some recipes take it a step further adding further flavor enhancers like: shitaki mushrooms, xaio xing, white pepper, and even fish sauce.

Chinese cured ham is very salty and and dry. Since it is cured raw you should always cook it very well before consuming. Smithfield country ham is an expensive substitute.  Although several sites said that it is illegal to import it to the US, one of my local Chinese markets carried it. In Chinese recipes, it is usually used as a flavoring, rather than the main meat in a dish.

The Filling

The most of the fillings, I found, for XLBs were fairly standard for Chinese dumplings. Pork or pork combined with shrimp with the usual set of seasonings—ginger, green onion, salt, soy sauce, and a touch of sugar. This is not to say that than you cannot make chicken or vegetarian versions of this dish.

Note: One of the recipes used whole tiny shrimp, instead of chopping up larger shrimp. This amused me, so I included it in my recipe.

Jan is constantly pushing me to add more vegetables to most of the recipes I make. many of the recipes for XLBs that I found had very little in the way of vegetables matter. A few weeks ago, I found a technique for salting napa cabbage to reduce its volume—allowing you to add more vegetables in less space. I decided to use that technique for my soup dumplings.

Napa cabbage does double duty in this recipe. The white parts are finely diced and salted to be added to the filling. Salting the cabbage leaches out much of the fluid in the fleshy stems. This both reduces their volume and prevents their excess liquid from diluting the soup.

The leafy parts are used to keep the XLBs from sticking to the steamer tray. When you steam dumplings they tend stick to the tray, usually cheese cloth or parchment paper is used to act as a barrier. By using the leafy parts of the cabbage as this barrier you do not have to risk tearing open your XLB when you remove it from the tray—an edible solution that you just leave attached to the dumpling.

The Wrapper Dough

The dough is the regular hot water dough that you make for any Chinese dumpling. Flour, salt and  warm water that is then kneaded until smooth and elastic. Since this dough usually has only three ingredients—flour, salt, and water—you would think this would be simple.

There was, however, very little agreement between recipes on how to make the dough for the wrappers. Some recipes used AP flour, cake flour, bread flour, or a combination of flours. I found one source recommending Chinese dumpling flour—a very white, high protein flour. Some recipes left out the salt and others added oil. There was even confusion on how to use the water. Should you use warm or hot water?

No one seemed to understand “the WHY” of how they were making their wrapper dough. Flour is a very versatile ingredient and very small differences in ingredients and handling can produce widely different outcomes. I decided to understand what techniques made a wrapper dough that was easy to roll—but not too elastic—flexible—but strong—and that did not dry out too quickly.

Chinese have been making dumplings for a hundred years. Traditional dumpling flour is high protein, so a high protein flour—bread flour—must be necessary for “proper” wrappers. Those recipes that use oil are trying to use a variation of a pastry crust—which does not have the same properties as a dumpling wrapper. Salt is also necessary for developing the strong gluten bonds that are necessary for the strength that the wrappers must have.

Using warm water enhances the proteins’ ability to form the gluten bond needed for the dough to have strength. This is why the recipes that use it also use low protein flours. This is because it would create too much gluten—producing a wrapper that would be tough and chewy. While the dough would be very strong, the gluten structure would be so tight that you could not roll the dough out as thinly as you need to for a good wrapper and it would have a tendency to “snap back.”

How does using hot water effect high protein flour to allow it to produce a flexible wrapper? I finally found a site that addressed this question. While warm water helps gluten structures to develop, hot water actually blocks the “gliadin and glutenin—the proteins in flour responsible for creating gluten”—by denying them the water they need to form strong gluten bonds. The hot water goes to scalding the starches in the flour, activating a different chemical reaction starch gelatinization.

When hot water is added to flour, the starch granules quickly absorb the water molecules, swell and burst. This releases smaller amylose molecules, which loosely link up into polysaccharides, which form a gelatinous mesh. In terms of a wrapper  dough, you want to add only enough hot water to gelatinize part of the flour—producing a starchy sponge that is soft and very good at retaining water.

Note: After you stir the hot water into the flour, you are left with a lot of loose flour and sticky clumps of gummy paste.

The hot water does not damage the proteins in the gelatinized flour. They are still trapped inside the spongy network of polysaccharides. When you add cold water to the bowl the remaining flour starts to form a gluten network.

It is difficult for the gluten strands to link together because of the presence of the polysaccharide mesh. As you knead the dough—and with the help of the salt—more and more of the gluten strands link up around and through the polysaccharide network. This creates a duel mesh that is tender, strong, and retains enough free water to make it easy to roll out the dough and for the edges to stick together when you pinch them—without adding a messy water wash along the edges.

The Dipping Sauce

There are also differences in opinion as to which dipping sauce you should use with XLBs. Some recipes use only white vinegar, soy sauce and shredded ginger. Other recipes call for black vinegar, soy sauce and ginger. Still other recipes like to spice up the dipping sauce with sesame oil and chili. A sauce that includes chili is a Sichuan dipping sauce.  Xiao long bao is a Shanghai dish and calls for a sauce without chili.

Rolling, Filling and Steaming

You should not roll the individual wrappers into a flat disc. After rolling the disc to about 2½ inches, you roll out the edges more thinly—you want to end up with a slight hump in the center of the disk. The hump in the center becomes the bottom of the dumpling. If the edges were not thin, most of the dough would end up at the top, when you gather the edges together to seal the dumpling.

You place a tablespoon of meat and soup cubes in the center of the of the dough disc. You might reserve some of the soup cubes to add to the scoop of filling if a particular dumpling seems a bit short on soup. You then gather a small fold along the edge and pinch it together. Continue folding and pinching until the dumpling is sealed. Ideally you should make 18 pinches to seal the dumpling—this is a lucky number in China.

When you steam any kind of dumpling they tend to stick to the steamer. You can use cheese cloth or parchment paper as a liner to prevent this. However, with those techniques you risk tearing the dumpling as you try to free it from the liner—for a soup dumpling this would be a very bad thing, leaking the soup back into the serving dish. Many xiao long bao recipes called for using pieces of cabbage to make it easy to remove the dumplings—an edible liner.

To steam the bao, you bring the water to a boil before putting on the steamer tray(s)—you may stack as many as four trays on top of each other. Steam the soup dumplings for 8-9 minutes.  When you serve the dumplings, remove both the pot and steamer tray(s) to the table. The residual steam will keep them warm until you eat them.

The Eating

There are wrong ways and a right way to eat XLBs. Do not simply bite in to the bun. If it has been served properly—i.e. straight from the steamer—it will flood your mouth with scalding soup. You are also not supposed to put it in a bowl and pop it open to let the soup drain out. The correct way is to hold it in your Chinese spoon and nibble a hole in the wrapper. You then sip out the soup. You may then add some of the dipping sauce and—after the dumpling has cooled slightly—gobble it down.

Note: I made a napa cabbage and carrot salad as a side dish to this meal.

After Dinner Note: I made about nine dumplings per person. None of them survived to be leftovers.

Karl’s Xiao Long Bao (aka XLB or Soup Dumplings)

Ingredients

The Soup

½ lb. pork skin
1 lb. chicken skin and bones
2 oz.  Chinese cured ham
4 cups water
2 green onions
1½ in. piece of ginger
1 cloves garlic, smashed
2 Tbs. soy sauce
2 Tbs. xaio xing rice wine
White pepper, ground, to taste
Kosher salt, to taste

The Filling

4-6 leaves napa cabbage, white parts only, finely diced
½ tsp. Kosher salt
1 lb. course ground pork, room temperature
2 Tbs. hot water
¼ tsp. baking soda
3 green onions, finely minced
2 cloves garlic, grated
1 tsp. fresh ginger, grated
2 Tbs. soy sauce
1 Tbs. xaio xing rice wine
1 tsp. dark sesame oil
½ tsp. sugar
¼ tsp. white pepper
4 oz. tiny shrimp, whole

The Wrapper Dough

3¼ cups  bread flour
½ tsp. Kosher salt
¾ cups boiling hot water
⅓ cup cold water

The Dipping Sauce

¼ cup black vinegar
¼ cup soy sauce
1 tsp. sesame oil
2-inch piece of fresh ginger, shredded

Directions

The Soup 

1. Fill a medium pot with water and bring it to a boil.

2. Put the pig skin in the pot and boil it vigorously for 5 minutes.

3. Put the chicken pieces on a lipped baking sheet and broil the skin and bones until well browned on all sides.

Tip: Flip the pieces frequently, so that you do not burn any of the chicken bits.

4. Remove the pig skin and let it cool and scrub away any scum.

Tip: Dump out the water and scrub the pot, before using it again.

5. Cut all of the fat from the skin.

Tip: The first boil will have softened the half an inch of dense fat on the inside surface of the pig skin, making it easier to remove. If there is any meat on the fatty side of the skin, trim it free and return it to the pot.

Note: The skin will be about ⅜ of an inch thick after your remove the fat.

6. Return the skin to the pot, add the chicken scraps and Chinese ham.

7. Add 4 cups of water to the pot.

8. Cut the green onions into three parts and smash them with the flat of a clever.

Tip: Breaking the cell walls of the onions frees the juices.

9. Cut the knob of ginger in half lengthwise and smash the pieces with the clever.

Tip: Laying the semicircle of ginger with the cut side down and curved side up prevents it from sliding around as you smash the root.

10. Add the green onions, ginger, garlic, soy sauce and wine to the pot.

11. Bring the pot to a boil, cover, and reduce the heat.

12. Simmer the soup for 30 minutes.

13. Remove the pig skin from the pot and slice it into small strips.

Tip: When the skin it raw it is very hard to slice it into small pieces. After it has cooked for a  while it become much softer.

Note: You are trying to extract as much collagen/gelatin as you can from the skin. The more surface area that is exposed the faster you can free it.

14. Return the skin to the pot and continue simmering the soup for another 3 hours.

15. Strain the solids from the broth and season with pepper and salt to taste.

Tip: You should be left with about two cups of soup at this point.

Note: If you used fatty pork or chicken skin de-fat the broth—by letting the fat rise to top and then blot it up with some paper towels. A little fat is flavor, but you do not want greasy dumplings. Also, if you wish, you may recover and mince the Chinese ham very finely to add to the dumpling filling.

16. Pour the soup into a shallow pan and cover it with plastic wrap.

17. Refrigerate the soup until it has fully set, at least two hours.

Tip: Over night is better.

18. Cut the aspic into small pieces—about ¼ inch dice—and remove it from the pan.

Tip: Cover and refrigerate the soup until you are ready to add it to the filling.

The Filling

19. Four hours before dinner, trim the napa cabbage leaves.

Tip: Cut each leaf crosswise about a third of the way down. Divide this leafy part in half lengthwise and put it in a bowl of cool water to keep it fresh. Reserve this for later when you assemble the dumplings.

Note: Four hours is just an estimate. It takes time to make the filling and dough, but the real labor is in rolling out the wrappers and filling them.

20. Cut the white parts of the cabbage into a fine—⅛ inch—dice.

21. Put the diced cabbage in a small bowl and sprinkle the salt over it.

Note: You want about ¾ of a cup of the diced white parts before you salt them. After being salted and drained this will reduce to about a third of a cup. You will need more of the leafy parts than the white parts—my solution for the extra cabbage was to make a side salad to go with the meal.

22. Toss the cabbage to distribute the salt and let it sit for 20-30 minutes.

Tip: Re-toss the cabbage every five minutes or so to redistribute the brine solution.

23. Put the cabbage in a large mixing bowl and add the pork.

Note: The Asian market I go to has two grades of ground pork. The finely ground pork is just what you would find in any supermarket. They also have a coarsely ground pork with easily identifiable small chunks of pork. I prefer to use this when making pork tacos and jiaozi for the extra texture it provides.

24. Mix the hot water and baking soda.

Tip: The baking soda raises the pH of the meat and allows it to retain more liquid as it cooks.

25. Mix the hot water solution into the meat.

Tip: The warm water softens the fat in the meat, making it easier to mix in the other ingredients.

26. Stir in the green onions, garlic, ginger, soy sauce, xaio xing, sesame oil, sugar, and white pepper into the meat.

Tip: Be a little rough here. You want to break down the meat a little bit, so that it sticks together as it cooks. You also want all of the little vegetables bits evenly distributed though out the mixture.

27. Fold in the tiny shrimp and the jellied soup bits.

Tip: Here you want to be a little gentile, so that you do not mash up the shrimp.

28. Cover the meat mixture and let it rest in the refrigerator for half an hour to firm up.

The Wrapper Dough

29. Put the flour in a large mixing bowl and thoroughly mix in the salt.

30. Pour in the hot water and stir it in with chopsticks or a fork.

Tip: The dough will be very ragged with a fair amount of dry flour left.

31. Add the cold water and stir it in with chopsticks or a fork.

Tip: The dough will be still be very ragged with just a small amount of dry flour left.

32. Turn the dough out onto a lightly floured flat surface and knead the dough for at least 15 minutes.

Tip: This will be a very tiring exercise. You may make it easier by wrapping the dough in plastic wrap—half way through—and letting it rest for 10 minutes—while you rest yourself.

Note: The polysaccharide mesh makes it difficult  for the gluten strands to link up. It takes a lot of kneading to form a good gluten network.

33. Knead the dough until it is smooth and slightly tacky.

34. Form the dough into a ball and lightly dust it with flour.

35. Wrap the dough in plastic wrap and letting it rest for 20 minutes.

Note: While the dough is resting set up an assembly station. You will need a floured flat surface and a small rolling pin. Put the meat mix with a spoon on one side, the cabbage pieces—drained and dried—and a steamer basket on the other.

Finishing Off the XLBs

36. This is a good time to prepare your dipping sauce, so that it will have time to meld.

Tip: Pour the dipping sauce into individual small bowls—one per person.

Note: Individual bowls of sauce reduces the amount of dripping and preserves your tablecloth.

37. Lightly flour the board and divide the dough in half.

Tip: Re-wrap the other half in the plastic, so that it does not dry out.

Note: Here is a good video on rolling out the wrappers.

38. Roll the dough into a snake, about an inch in diameter.

39. Cut the dough snake into approximately ¾ inch pieces.

40. Dust the pieces with flour and flatten them.

Tip: Cover the ones you are not rolling out with a damp towel to prevent them from drying out.

41. Taking one piece at a time, roll it into a 3-4 inch round.

Tip: You roll the individual wrappers so that you end up with a slight hump in the center of the disk.

42. Place about 1½ tablespoons of meat and soup cubes in the center of the of the round.

Tip: You want about ⅓ meat mixture and ⅔ soup cubes per dumpling.

Note: It is a good idea to reserve some of the soup cubes to add to lean dumplings. I did not do this and several of my XLBs came up “dry.”

43. Gather up a small fold along the edge and pinch it together.

44. Continue folding and pinching until the dumpling is sealed.

Tip: Here is a video of the proper folding technique.

Note: Ideally, you should make 18 pinches to seal the dumpling—this is a lucky number in China.

45. Twist the folds at the top to completely seal the XLB.

46. Place the dumpling on a piece of cabbage leaf and set it in the steamer basket.

47. Continue rolling, filling, sealing and placing the buns in the steamer basket until it is full.

Tip: You do not want to crowd the basket. I put 15-16 buns per steamer tray and I used 3 trays.

48. About 15 minutes before serving, set up you’re your steamer pot.

49. Bring the water to a boil before putting on the steamer tray(s).

Tip: You may stack as many as four trays on top of each other.

51. Steam the soup dumplings for 8-9 minutes.

52. When you serve the dumplings put both the steamer pot and steamer tray(s) on the table.

Tip: The residual steam will keep them warm until you eat them.

53. Enjoy immediately—while they are still hot—with the dipping sauce on the side.