The dough for xiao long bao 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.
Karl’s Xiao Long Bao (The Wrapper Dough)
3¼ cups bread flour
½ tsp. Kosher salt
¾ cups boiling hot water
⅓ cup cold water
1. Put the flour in a large mixing bowl and thoroughly mix in the salt.
2. 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.
3. 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.
4. 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.
5. Knead the dough until it is smooth and slightly tacky.
6. Form the dough into a ball and lightly dust it with flour.
7. Wrap the dough in plastic wrap and letting it rest for 20 minutes.
Note: While the dough is resting set up an assembly station. Put the meat mix with a spoon on one side, the cabbage pieces—drained and dried—and a steamer basket on the other.