Karl’s Tom Yum Kathi

Adapted from a RasaMalaysia recipe

I have decided to do Thai food for this week’s Sunday dinner. While I have had tom yum soup at Thai restaurants, I have never tried to make it myself. This Thai standard is a hot and sour soup usually made with shrimp—although there are many variations. Tom yam kathi (Thai: ต้มยำกะทิ) is basically Thai tom yum soup with coconut milk added to it.

Karl’s Tom Yum Kathi

Karl’s Tom Yum Kathi

Lemon grass adds an amazing flavor to soups, but it is very fibrous. While you can mince or grind it into tiny pieces for curry pastes or stir-fries, you generally do not want tough, chewy pieces of it in your soup. Here is a good video on preparing lemon grass for soups and other uses.

Galangal is an aromatic rizome like ginger. While they may appear very similar, their taste and texture is very different—galangal is has a citrusy flavor and is paler and tougher than ginger. While I have seen recipes that suggest substituting ginger for galangal, they are really very different and I do not suggest it.

Note: The link I just cited, says that galangal cannot be grated. For my sate sauce, I used a very sharp microplane and had no trouble doing so—I worried that my blender would not be able to break down the slices of galangal on its own.

Bird’s eye chilies are uses extensively in Thai dishes. While they have a fruity flavor, they are very spicy—up to 100,000 Scoville units. If you get their juice on your fingers and rub near your eye you will deeply regret it. Be sure to use latex gloves if you cut open these chilies!

After Dinner Note: While this soup came out phenomenally—as good as any Thai restaurant soup I have had, my other dishes were not quite up to snuff. I usually post all of the recipes in my Sunday dinners. This week’s Gai Lan Pad Thai and Sate Chicken wings were not even “good” bad examples—so I will not disappoint my readers by posting them. I did learn a new recipe for a Thai Peanut Sauce that is very different from the one I use for Vietnamese Summer Rolls.

Karl’s Tom Yum Kathi


4 cups shrimp stock (see note step 1)
1-2 stalk lemongrass, cut into 3-inch strips, pounded with a cleaver

3 Tbs. fish sauce
3 Tbs. lime juice
1 Tbs. nam prik pao, Thai roasted chili paste
6 kaffir lime leaves, bruised
3-4 bird’s eyes chilies, cracked
3 big slices galangal

3 oz. white beech mushrooms

1 cup coconut milk
3-5 shrimp per person

Toppings on the side

Fresh cilantro leaves
Fresh basil leaves
Lime wedges


1. Prepare your shrimp stock.

Tip: There are two ways to do this. First—and most authentically—you may buy head one shrimp and them boil and strain them to make your stock. The second way is to get a bit more eclectic. I found Consome de Cameron at my local Mexican market. One teaspoon per cup of water makes an excellent shrimp broth.

Note: I started my stock with six cups of water and 3 tablespoons of consome powder. After adding the lemongrass I simmered the stock down to about 4 cups of liquid to make a hearty broth.

2. Add the crushed lemon grass to the pot and simmer the stock for 30-40 minutes.

Tip: If you are using shell on shrimp, peel the shrimp and add the shells to the stock at this point. Every little flavor boost helps.

Note: Do not add the shrimp meat to the soup at this time. Put it in a covered bowl and refrigerate until adding the shrimp to the soup during the last few minutes of cooking.

3. Strain the solids out of the broth.

Tip: I pour the soup through a fine mesh sieve and then press any liquid I can out of the solids, before discarding them. If you wish to remove the grit that results from using the Consome de Cameron—it is basically ground up dried shrimp—you may strain the broth a second time through a superfine tea strainer as you return the broth to the pot.

Note: I tried using a paper coffee filter—to get a clear shrimp broth—but it clogged up almost instantly.

4. While the stock is simmering, measure the fish sauce, lime juice, chili paste, lime leaves, bird’s eye chilies, and galangal into a cup.

Tip: This pre-measuring makes it easier to add everything to the soup at once and also gives these ingredients time to meld. I added the bird’s eye chilies whole, but if you like a really spicy soup, you may crack them open or even slice them up.

Warning!!! Be sure to wear latex gloves, if you open the bird’s eye chilies!

Note: This soup was so popular that Eilene requested it again for when her friends came over. In this second attempt, I thought that adding the galangal to the stock with the lemongrass would be a good idea. It turned out “not so much,” the flavor of the galangal swamped the more delicate flavor of the lemongrass when it was simmered too long.

5. Add the mushrooms and contents of the reserved cup to the soup.

Note: Many of the recipes I looked at called for using canned straw mushrooms. While this may be the traditional ingredient, it is difficult to get these fresh in the U.S. I decided to substitute with white beach mushrooms.

6. Simmer the soup for another 10 minutes.

7. Add the coconut milk to the soup to taste.

Tip: Coconut milk is fairly sweet and this is a hot and sour soup. Look for a balance of the flavors that suits your taste.

Note: In my second attempt at making this soup, I added the entire 14.5 oz. can to the soup. The sweetness washed out much of the other flavors—the result was disappointing and certainly not as good as my first attempt. Add the coconut milk slowly, tasting as you go.

8. Stir in the raw shrimp and simmer the soup for another 2-4 minutes, until the shrimp are cooked through.

Tip: Do not overcook the shrimp or they will become tough and chewy.

Note: Fish out the lime leaves and bird’s eye chilies before serving. The leaves are too tough to chew and—unless you are really brave—the chilies are too hot to eat whole.

9. Serve the soup in individual bowls with the cilantro, Thai basil, lemon wedges and sriracha on the side.

Tip: I served my Thai basil as whole leaves—as I had seen in some recipes. My diners complained that they were difficult to eat that way. Shred the leaves finely—just before serving—so that they do not wilt and brown.

Note: If you wish to turn this starter into a main dish, you may add rice stick noodles and more fresh vegetables, like bok choi, to the bowl before adding the soup.

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Filed under Shrimp, Side Dishes, Soups

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