Tom kha gai is often called Thai coconut soup in English since this simple soup is smooth and rich with coconut milk. But the flavors are so much more than that, with an aromatic broth base, infused with lemongrass, chili, galangal and lime leaves. It's quick and easy to make, with a delicious mix of bright flavors and comfort factor.
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Thai cooking has a few soups that are packed with the flavors of the region. This makes them different from many European soups as they have a different mix of flavors, including spicy and sour.
This lovely soup is a great introduction as it's a little less spicy than some and also easy to make. True, you need a few less typical ingredients, but once you have them, it comes together with minimal effort.
What does tom kha gai mean?
While the soup is often called Thai coconut soup or coconut chicken soup, that's not actually the translation of the Thai name. "Tom" means "boil" and so refers to the process of making the broth base. "Gai" means "galangal" which is one of the main flavors in the broth. "Gai" means chicken as that's the protein used in this version.
The first written version of the soup was in a Thai cook book in 1890 and was tom kha pet, made with duck. These days, chicken is probably the most common but other versions exist, too. You can make it with other proteins in there, for example tom kha kalay with seafood, tom kha mu with pork, or tom kha taohu with tofu.
The dish is often said to be originally from the North or Thailand, though the exact origins are unclear. You also find this soup in Laos, since there has historically been overlap in teritory and cusine between Northern Thailand and Laos.
What is the difference between tom yum and tom kha?
Tom yum is another popular Thai soup, and possibly the best known elsewhere. Both that and this soup start with the same process of making a herb/spice-infused broth. But tom yum is spicier and often called a hot and sour soup. It is not creamy but instead has a clear broth. The most common version is tom yum gung, made with shrimp.
Tom kha, meanwhile, is made with coconut milk which gives it a creamy, smooth finish. It is also less spicy. You can also easily dial down the heat even more when you make it yourself, if you like, making it a great introduction to Thai food for those less able to handle spice. While chili is classically in the mix, even with none it has a great aromatic flavor.
About the ingredients
As mentioned, the base of this soup is essentially a stock base (use a good chicken stock, homemade if possible), infused with aromatics. You then cook the chicken and other ingredients in the broth. Even though some of the ingredients may be less familiar, you can probably find most if not all in your local Asian supermarket.
- Galangal - As mentioned above, galangal is part of the name of the soup, so a key ingredient. While in the West ginger and galangal are sometimes used interchangeably, Thais would disagree. Ginger (khing), is not right for this soup to have an authentic flavor. While it can be a little hard to find, most Asian stores will stock galangal. If you are having difficulty finding fresh, using dried galangal powder is probably better than substituting with ginger. Galangal is generally a little less spicy and more citrusy in flavor compared to ginger.
- Kaffir lime leaves - also known as makrut lime leaves. These are the leaf from a particular type of lime that has quite a nobly skin. Both the lime and the leaves are common in Thai cooking, as well as other cuisines of the region. While you can sometimes get dry leaves, look for the fresh ones for this. They really are so much better flavor-wise. They are pretty widely available in Asian stores, usually sold by the fresh herbs.
- Lemongrass - this is another common Asian ingredient with a lovely lemon-like aroma (hence the name). In some dishes, you grind it or finely chop it, but for this you just want lengths from a stem to help get some flavor into the broth. These days, the stems are pretty widely available.
- Chili - use the small Thai red chili for this, or green if that is all you can find. If you can't find either, then use another relatively hot fresh chili. You can, of course, adjust the chili to taste, but this is a relatively spicy soup.
- Fish sauce - while you get plenty of fishy flavor from the broth, this adds a greater depth and slightly salty-umami flavor.
- Coconut milk - this adds the signature creaminess to the soup. Make sure you use a good quality, thick one to get the best finish to the soup. Authentic Thai brands are often the best options.
- Chicken, mushrooms and onion - these are all fairly typical, readily-available ingredients and add the 'bulk' to the soup. In terms of chicken, opt for thigh meat as it has more flavor. Straw or oyster mushrooms are most typical, but you can use others if not available.
- Lime juice and cilantro - these add a lovely freshness to the soup. Only add the lime juice in particular right before serving, so the flavor is brighter. If you will be storing some of the soup, don't add the lime until you reheat and serve.
Some recipes use a Thai red curry paste in the soup but that's not part of the traditional recipe. You get plenty of flavor from all those wonderful spices infusing the broth base.
As mentioned, the trickiest bit of this soup is probably getting the ingredients, as after that it's all easy. The only things you really need to think about are getting things ready in advance, and adding in the right order so everythnig cooks properly.
Can you make this soup ahead?
Yes you can! This soup is great to make ahead, or make extra, and store in the fridge for another time. Keep it refrigerated in a sealed container for up to 5 days then just reheat on the stovetop or in the microwave to warm it through. The flavors only infuse the broth more so it can actually almost be better a day or two after making it.
Top tip: add the lime last
As mentioned above, don't add the fresh lime juice until you are about to serve it. One good option is just adding it in the bowl so that if you might have leftovers, that part of the soup doesn't have lime in yet. This keeps the flavor from the lime fresh (and helps avoid any possibly separation it may cause with the coconut milk).
If you are re-heating, you may also want to add a few extra cilantro leaves when you serve it so you get their extra freshness in there.
Tom kha gai is a wonderfully flavorful, comforting soup with bright aromatic flavors. The combination of chicken, coconut and and a spice-infused broth are so good. Easy to make and easy to enjoy.
Try these other tasty soups:
- Sopa de lima (Mexican lime soup with chicken and tortilla chips in a tasty broth)
- Pea and mint soup (a super easy, bright and light soup)
- Cullen skink (a classic Scottish soup, essentially a smoked haddock chowder)
- Plus get more appetizer recipes and Southeast Asian recipes in the archives.
Tom kha gai (Thai coconut soup)
- 1 ½ cups chicken stock
- 1 stalk lemongrass
- 4 slices galangal or less if large
- 4 makrut lime leaves (also called kaffir lime leaves)
- 2 Thai red chilis
- ½ lb boneless chicken thighs
- 3 oz oyster mushrooms
- 1 cup coconut milk look for a rich, thick milk eg Thai brands
- 1 teaspoon sugar
- 1 tablespoon fish sauce
- 1 tablespoon lime juice freshly squeezed
- 1 stem cilantro coriander, approx - for garnish
- Place the stock in a medium sized pot. Trim the ends off the lemongrass stalk, then bruise the lemongrass, galangal slices and chilis with a mortar or small mallet so open them up a little then add all to the stock. Tear two of the lime leaves then add to the stock as well.
- Cover the pot with the stock and aromatics and place over a medium heat and bring to a simmer. Meanwhile, cut the chicken into a relatively small dice.
- Once the stock is simmering, add the chicken and stir to separate the pieces. Bring back to a simmer and cook around 15 minutes until the chicken is cooked through. Reduce the heat if needed so that the mixture simmers rather than has a roaring boil.
- As the chicken cooks, clean and slice the mushrooms and trim off any tough stems. Once the chicken is cooked through, add the mushrooms to the pot along with the coconut milk and remaining whole lime leaves.
- Stir the mixture to mix, cover and cook a minute or two more then add the sugar, fish sauce and lime juice. Mix through, taste and adjust the seasonings if needed. Note if you are not serving all immediately, it's better to just add the lime juice in the bowl and store leftovers without the lime juice added.
- Serve the soup topped with a few torn cilantro leaves as garnish.
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