Tom Kha soup. It is without a doubt, along with Tom Yum, the most well-known Thai soup and one of the most famous Southeast Asian soup recipes. In this post, I’m gonna show you how to make the most basic, simple version of Tom Kha soup at home, known as Tom Kha Gai. The recipe is inspired directly by my travels to Thailand, where I learned to make it. But it’s so easy that you don’t have to travel to Thailand to make an authentic version in your own kitchen!
Tom Kha Gai is a Thai chicken coconut soup. In the Thai language, tom means to boil, kha means galangal, and gai means chicken. In case you’re wondering, galangal is sometimes referred to as Thai ginger, and while there are similarities, galangal has a different flavor, aroma, and texture (more on that below). But there’s a lot more to Tom Kha Gai than boiled chicken and galangal.
The soup features the four classic S flavors of Thai cuisine — salty, sour, sweet, and spicy. Typically though, it’s not a super spicy soup. In fact, it’s more on the mild side and that’s probably why it’s so popular in western Thai restaurants.
In my opinion, the best versions of Tom Kha soup recipes balance those four flavors equally. However, as with all traditional recipes, infinite variations and interpretations abound. Some feature one or a few of those flavors more predominantly.
In my many trips to Thailand, I’ve experienced quite a variation in styles. Some were thick and more coconut milk-based, some thinner and more broth-based, some ultra sweet, some just a tad sweet, some with a lot of lime juice, some with very little, some with fish sauce, some without fish sauce, some super spicy and some not spicy at all.
What’s most important is finding a balance of flavors that YOU like. For that reason, I try to leave room in my Thai soup recipes for you to include more or less of those four classic flavors. I’ll explain how to do that below. It’s quite easy. But let’s discuss what’s NOT open to interpretation.
Those four ingredients above — galangal, lemongrass, kaffir lime leaves, and bird’s eye chiles — are truly key to any Tom Kha soup recipe. Galangal is pictured on the left. Lemongrass is pictured on top. Kaffir lime leaves are on the lower right. I hope the chiles are obvious. 🙂
In my Thai cookbook, The Thai Soup Secret, I call lemongrass, kaffir lime leaves, and galangal The Triple Gem (a Buddhist reference) of Thai soups. They are quintessential to not just Tom Kha but to Tom Yum and so many other Thai dishes. For example, if you’ve ever had a Thai curry paste, such as a green or red curry paste, they almost always include the triple gem of Thai soups.
All three are used to infuse Tom Kha with their highly pungent flavors and aromas. Now they’re not really meant to be eaten in soups. Typically, you either remove them before eating or just spoon around them. If you accidentally chomp into one, you’ll probably know it as they’re somewhat tough and fibrous. Just know they are edible and won’t hurt you.
As for the small red bird’s eye chiles, they’re so iconic to Thai cuisine that they’re sometimes just referred to as Thai chiles.
Let’s discuss each one of those four key ingredients separately, how to prepare them for Tom Kha, and the best places to find them.
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Lemongrass has a highly pungent citrus character. It’s not that hard to find fresh lemongrass these days. It’s frequently sold in places like Whole Foods as well as specialty health food stores. It can always be found in Asian supermarkets. You can also find fresh lemongrass on Amazon.
You’ll need three lemongrass stalks for this Tom Kha recipe.
Lemongrass is similar to leeks in that the stockier bottom half is the part we use. Simply slice the lemongrass stalk in half and either discard it or, better yet, save the thin green upper half for soup stocks. You’ll be left with a 6- to 8-inch piece.
Next, slice about a half inch off from the hard bottom end. Remove the fibrous outer layer, which will expose the more tender and pungent inner part.
Very lightly bruise the lemongrass with a meat hammer or any flat, dull kitchen utensil. This will break down the cell walls and help to release the essential oils. Then slice the stalk into about 1/4-inch smaller rings, at about a 45-degree angle (in the culinary world this is called “on the bias”), which will create more surface area.
Also used as an aromatic, galangal is a rhizome in the ginger family. While galangal resembles ginger in appearance it has a more citrus, peppery flavor. It also has a different aroma. It’s hard to describe but I think it smells like a pine forest. It also tends to be a bit woodier and thus tougher than ginger which is also why it’s ideal for use in soups.
Many people ask if ginger can be substituted for galangal. It can but it will add a sharper quality and flavor. Furthermore, it’s called Tom Kha soup for a reason. Remember, kha means galangal. So really try to find galangal for this recipe.
Galangal can be more challenging to find in supermarkets. Your best bet will be an Asian supermarket. But you can also find fresh galangal on Amazon.
It’s quite simple. Peel the outer skin and then slice it into small circles, about an inch in diameter and about a ¼ to ½ inch thick, like so…
Kaffir lime leaves, also called makrut lime leaves, are best used fresh and give soups a hint of lime but are nothing like using actual lime juice which should not be used as a substitute. They have their own distinctive aroma and flavor which is hard to describe! They are small, dark green, somewhat shiny, and grow with two leaves connected together.
Kaffir lime leaves are also hard to find outside Asian markets. Luckily, you can easily find fresh kaffir lime leaves on Amazon.
Even simpler than galangal, just tear each leaf into a few pieces. This will begin to release their essential oils. When you do this, you’ll smell their wonderful fragrance! Again, it’s hard to describe but if you’ve ever had Thai cuisine, you’ll immediately recognize it.
These small hot chiles, about 2 inches long, are really intense! They are the classic chiles used in Tom Kha soup recipes and can be found in many supermarkets, both conventional, and health food stores, and almost always in Asian markets. You can also find fresh Thai chiles on Amazon.
Be careful when using fresh bird’s eye chiles! Everyone’s tolerance for heat and spice is different. Simmering even just one bird’s eye chile in a soup can dramatically increase the heat level.
It’s totally up to you. Again, Tom Kha is not traditionally ultra-spicy. So if you have absolutely zero tolerance for hot and spicy foods, just leave them out. No big whoop.
For a mild kick, use only one Thai chile. For a medium kick, use two. And for a really good kick, use three or more.
It should also be noted that many Tom Kha recipes include sliced Thai chiles on the side so that each person can add as much or as little as he/she wants.
Classic Tom Kha Gai recipes always include Thai bird’s eye chiles. But any type of chile can be used as a substitute especially where there is an intolerance or just a dislike for spiciness.
The ones I commonly recommend in place of bird’s eye chiles are jalapenos and serranos both of which are often found in conventional supermarkets, especially jalapenos. Serranos are slightly smaller and usually a good bit hotter than jalapenos which can range from mild to moderately spicy.
Slice the chiles lengthwise, like so…
You can also scrape out the seeds inside the chiles which will help tone down their heat.
So we also have coconut milk, limes, an onion, tomatoes, and mushrooms. The only thing not pictured is the chicken and chicken broth. Also, cilantro and green onions, which are optional garnishes.
Also, jasmine rice is often served on the side with Tom Kha soup recipes.
This simple Tom Kha Gai recipe is inspired by the island of Koh Lanta in southern Thailand. The Thai family that ran the guesthouse where I stayed made the best version I had anywhere in Thailand. They even let me come into the kitchen to teach me how to make it.
What I love about it is the balance of the 4 S flavors and the ability to adjust things to your personal tastes.
I was surprised by just how simple it was to make! It all comes together in just a handful of steps. The following ingredient amounts are for a serving size of 6 people.
Have everything peeled, chopped, and ready to go, as shown in the pictures above. You can also dice and prepare the veggies too.
If you’re using raw, uncooked chicken, add the chicken to the broth, and simmer it for about 5 minutes. If your chicken is already cooked, we’ll add it in step 4 below.
Raise the heat to a gentle simmer. Make sure to not boil the coconut milk which can easily curdle. Simmer everything gently for about 10 minutes to let the herbs infuse the soup.
Remember, be careful with Thai bird’s eye chiles. Add only one for a very mild dose of heat. Add two for a medium dose, and three or more for a more spicy version. You can also chop up some raw Thai chiles and add them at the end.
Let the veggies cook for about 5 minutes. This will keep them from turning overly soft and mushy. Cook it a little longer if you like them more fully cooked.
If you’re using pre-cooked chicken, add it with the veggies.
If you’re cooking for a group of people, it’s always better to be cautious with the seasonings and allow each person to season their individual servings to taste.
Now, add 2 TBSPs of fish sauce, 2 teaspoons of coconut palm sugar (granulated or block form), and 2 TBSPs of freshly squeezed lime juice. Gently stir them in.
Taste. Ask yourself what flavor you’d like more of. Keep in mind those starting amounts are fairly conservative. Personally, I would add a bit more lime juice and fish sauce. In particular, I would add at least another 2 TBSPs each of fish sauce and lime juice. Coconut milk is fairly sweet so I don’t think much more sugar is needed.
As for the chiles, I like things moderately spicy so I would’ve added 2 Thai chiles back in step 2. But if you’re craving a little more kick, add in more chiles right here. Or, just add fresh chiles to your individual serving.
Finally, add some cilantro and/or green onions and stir them in.
That’s really all there is to it!
The main difference is that Tom Kha includes coconut milk and Tom Yum does not. Both feature similar ingredients including the three herbs and Thai chiles. The most common version of Tom Kha is Tom Kha Gai and The most common version of Tom Yum is Tom Yum Goong (goong means shrimp in Thai).
Of course! Tom Kha soup recipes often include shrimp, in which case it would be called Tom Kha Goong (goong means shrimp in Thai). But you could use almost any protein you want including combinations of proteins. It’s not unusual to find Tom Kha soup recipes with both chicken and shrimp. Vegetarian versions are pretty popular too.
Jasmine rice! It’s the ideal complement and side dish. In Thailand, Tom Kha is always served with rice on the side. But if you want to vary it up any type of salad would work just fine.
Yes, pretty much any type of vegetable is fine. Most traditional Tom Kha soup recipes include some combination of onions or shallots, tomatoes, or mushrooms.
Because the lemongrass, galangal, and kaffir lime leaves will continue to infuse the soup. You should notice a heightened flavor the day after. It’s called aging or curing. It’s very common in many types of soups, including chowders.
Yes, they all freeze very well. You will often have to purchase more of each than you’ll need so freezing them will preserve them for your next Tom Kha or other Thai recipe.
This recipe for a Tom Kha Gai, the classic Thai coconut chicken soup, is easy to adjust to your personal taste, especially if you don’t like spicy!
Bring the chicken broth to a simmer. If you're chicken is raw, add it here and cook for about 5 minutes.
Add the coconut milk, lemongrass, galangal, kaffir lime leaves, and Thai chiles. Raise the heat to a gentle simmer. Make sure to not boil the coconut milk which can easily curdle. Simmer everything gently for about 10 minutes to let the herbs infuse the soup.
Add the veggies. Let the veggies cook for about 5 minutes. This will keep them from turning overly soft and mushy. Cook it a little longer if you like them more fully cooked. If your chicken is pre-cooked, add it here.
Add 2 teaspoons of coconut sugar, 2 TBSPs of lime juice, and 2 TBSPs of fish sauce. Taste. Add more of each, to taste. Add cilantro and green onions, optional.
Craig Fear is the creator of Fearless Eating and the author of three books, The 30-Day Heartburn Solution, Fearless Broths and Soups and The Thai Soup Secret. After years helping clients with digestive issues, Craig decided to pursue writing full-time. He intends to write many more books on broths and soups from around the world! Click here to learn more about Craig.
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