Tom Kha Gai Recipe

The Thai coconut milk soup known as Tom Kha Gai is as rich and creamy as it is light and refreshing. This juxtaposition of flavors is so enticing, it's no wonder this Thai soup is so popular, both in Thailand and throughout the world. Read on for an authentic recipe with all of the tips and tricks you need to make this delicious Thai soup.

I still remember the first time I had Thai food, some 20+ years ago. I was a college student and went out with a group of my dormmates to a local Thai restaurant. We ordered a smattering of dishes to share, and I remember liking them all, but ONE really stood out from the rest.

Yes, the soup that got me hooked on Thai food was Tom Kha Gai. I just love the contrasting flavors -- rich and creamy from coconut milk, yet light and refreshing from fresh lemongrass, galangal, makrut lime leaves, and lime juice. Add in some Thai chilis for a little spice, fish sauce for salt, and chicken and mushrooms to make it substantial and you have what may well be the most perfect Thai soup. It's certainly my favorite!

What is Tom Kha Gai?

Tom Kha Gai is a popular Thai soup made by infusing a creamy coconut milk broth with lemongrass, galangal, and makrut lime leaves. The resulting soup is rich and creamy, while at the same time tangy and citrusy. With tender bites of chicken and mild-flavored mushrooms, this soup is utter deliciousness and comfort in a bowl.

In Thai, Tom (pronounced tome) means "to boil" and is used to refer to soups. Kha is the Thai word for galangal and Gai is the Thai word for chicken. Put together, Tom Kha Gai is literally translated as Soup of Galangal and Chicken. (see How To Interpret a Thai Menu for more details). In English, however, Tom Kha Gai is more often referred to as Thai Coconut Milk soup.

Why You'll Love this Tom Kha Gai Recipe

• Authentic Thai Flavors: This recipe follows the traditional Thai cooking method of infusing galangal, lemongrass, and makrut lime leaves into a coconut milk broth, resulting in that characteristic citrusy flavor of Tom Kha Gai.
• Perfect Balance of Creaminess and Lightness: By using a 1:2 ratio of coconut milk to broth, the soup achieves a harmonious balance—rich and creamy without being overly heavy.
• Customizable Heat Level: By varying the number of Thai chilies and how they're prepared, you can control the soup's heat, making it as mild or as spicy as you like.
• Straightforward Preparation: Despite its complex flavors, this Tom Kha soup is relatively easy to prepare. You just simmer the broth with aromatics, add chicken and mushrooms, and finish with lime juice and fish sauce to taste.

Aromatic Ingredients

• Galangal: Galangal (known as Kha in Thai) is the key component of this soup and provides a sharp, earthy, somewhat citrusy flavor. Simply wash the galangal, cut a 1 inch piece off and slice it into thin rounds. You should wind up with about 10 round slices.
• Lemongrass: Lemongrass provides a wonderful lemony fragrance to this soup. Peel any dead outer leaves away from the main stalk, then cut the top ⅓ of the stalk off and discard. Cut the bottom ⅔ of the stalk into 2 inch lengths, then bruise with the back of a chef's knife to help release the fragrance.
• Makrut (Kaffir) Lime Leaves: Makrut lime leaves are another essential ingredient in this soup and impart a very distinctive citrus flavor. Wash the leaves, then fold them in half to strip the central vein away. If they are large, you can tear them in half again. Tearing is preferred to cutting as it releases more fragrance.
• Thai Chilis: The number of chilis you add, how strongly you bruise them, and when you add them to the soup will determine the spice level. One Thai chili added closer to the end of cooking will give you a mild spice whereas more chilis bruised and added while the aromatics simmer will result in a spicier soup.

Soup Ingredients

• Chicken Broth and Water: A combination of chicken broth and water forms the base of this soup. If you prefer a richer base, you could use all chicken broth. Store bought chicken broth is fine. Homemade Thai broth is even better!
• Coconut Milk: Coconut milk provides the creaminess. I've seen all kinds of recommendations for the amount of coconut milk you should use in this soup, from it being completely coconut milk based to using only a spoonful or two. As such, I have experimented with all of these variations.  I've found that using 2 cups of coconut milk per 4 cups of broth is the perfect amount of creaminess for us.  Even a spoonful more and my Thai husband will declare the soup "mun guen pai" (มันเกินไป) or too greasy/fatty.  Less than this and my more Americanized palate craves just a little more creaminess.
• Lime Juice: Fresh lime juice provides the tang that counterbalances the creamy richness of the coconut milk. Start with 1 Tablespoon and add more as needed, depending on how sour your lime is.
• Fish Sauce: Fish sauce provides the salty umami flavor for this soup. Again, start with 1 Tablespoon and add more as needed. Exactly how much you need will depend on how salty your chicken broth is.
• Chicken: Boneless, skinless chicken thighs and breast both work well in this soup. The chicken should be sliced into bite-sized pieces.
• Mushrooms: Any mild flavored mushroom will work well in this soup. Straw, champignon, beech, and oyster mushrooms are all good choices.

Tom Kha Gai Recipe

Tom Kha Gai is actually very straightforward to make once you have the right ingredients. Follow these six steps to a delicious Thai coconut milk soup:

Step 1: Start by preparing the fresh herbs. Cut the lemongrass into 2" pieces and bruise them. Slice the galangal into thin rounds. Tear the makrut lime leaves in half. Peel the shallots, and if they are large, cut them in half. Cut the stems off the Thai chilis.

Step 2: Next, infuse the chicken broth with the prepared herbs (except the Thai chilis). Allow the herbs to simmer on medium heat for 10-20 minutes until the aroma is strong. At this point, you can strain them out for ease of eating, or leave them in if you prefer a stronger flavor.

Step 3: While the herbs are cooking, wash and prepare the mushrooms. Depending on which mushrooms you use, they can be left whole (beech), cut in half (straw), or sliced (white button). Cut the chicken into bite-sized pieces. Add the chicken and mushrooms to the broth and allow to cook until both are cooked through and tender.

Step 4: Then add the coconut milk and stir until well mixed. You can turn the heat down to medium low at this point so that the coconut milk doesn't get too hot and separate.

Substitutions

Since galangal (Kha) can be hard to find, ginger is often suggested as a substitute in Tom Kha Gai. However, ginger does not taste the same as galangal, and makes a very poor substitute. I do not recommend using it. Fresh and frozen galangal both work well, and can often be found at local Asian markets.

Likewise, I don't know of a good substitute for fresh makrut lime leaves. These leaves are often available at markets catering to the Southeast Asian population. I have also spotted them at specialty markets like Whole Foods in our area. If you're not able to find them consistently, you might consider growing your own makrut lime tree for an endless supply of fresh leaves!

If you're not able to find these Thai herbs fresh locally, they are also sold fresh online, separately (lemongrass, galangal, makrut lime leaves) and as part of a kit. Dried herb kits are also available online, but they will not impart as much flavor as the fresh herbs. Therefore, I don't recommend using them.

Variations

Tom Kha Gai specifically refers to this soup made with chicken, as Gai means chicken in Thai. It is most traditionally paired with a variety of mushrooms, although you could vary the vegetables if you like. Green beans, kabocha squash, carrots, and bamboo shoots are all delicious in this soup. You could also make Tom Kha with different proteins such as pork (moo), shrimp (goong), or tofu (tau hu). Just be sure not to call it Tom Kha Gai!

Another variation that I enjoy is adding a Tablespoon or so of Thai roasted chili paste. Although this is not traditional, this all-in-one chili paste really adds a wonderful depth of flavor. You could also top the soup with a handful of cilantro leaves or chopped green onion if you like.

To make a vegetarian or vegan version of Tom Kha, you could swap the chicken broth for vegetable broth, replace the fish sauce with table salt or soy sauce, and omit the chicken. You could add cubes of tofu or another meat substitute, if you like.

Tom Kha Gai Recipe FAQs