Tom kha soup is the Thai restaurant order I make most often at home, and the slow cooker version is the one I actually cook on weeknights. Chicken thighs, coconut milk, lemongrass, galangal and lime leaves go in cold, and 3 hours later you have a broth that tastes like it simmered all day.
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The trick is treating the aromatics like a bouquet garni: leave lemongrass, galangal and lime leaves in big pieces so you can fish them out before serving. That keeps the broth fragrant without anyone chewing on a woody stalk.
I finish the soup with lime juice and fish sauce off the heat, because both turn dull and salty when they cook long. That single step is the difference between flat coconut soup and real tom kha.
Why You'll Love This Recipe
About the Ingredients
1 1/2 pounds (680g) boneless, skinless chicken thighs, cut into 1-inch pieces
Thighs stay tender through a long cook; breast works but add it in the last 45 minutes. Buy thighs labeled 'boneless skinless' so you skip trimming.
2 cans (13.5 oz / 400ml each) full-fat coconut milk
Full-fat is essential for body; light coconut milk makes a thin, watery broth. Shake each can hard before opening so the cream and water combine.
4 cups (960ml) low-sodium chicken broth
Use unsalted or low-sodium so you control the fish sauce at the end. Vegetable broth makes a fine vegetarian swap.
3 stalks lemongrass, outer leaves removed, cut into 2-inch lengths and smashed
Smash with the back of a knife to release the oils. No lemongrass? Use 2 wide strips of lemon zest plus 1 tablespoon lemon juice at the end.
1 piece (2-inch) fresh galangal, sliced thin
Galangal is sharper and more piney than ginger; fresh ginger is the closest substitute. Look for firm, moist slices at Asian markets.
6 makrut lime leaves, torn
Tearing releases the citrus oils. Frozen leaves beat dried; if using dried, double the count and add them with the broth.
8 oz (225g) cremini mushrooms, quartered
Creminis hold their shape; oyster mushrooms give a silkier bite. Wipe with a damp towel instead of rinsing so they do not soak up water.
1 medium red bell pepper, sliced into thin strips
Adds sweetness and color. A handful of cherry tomatoes tossed in at the end is a classic tom kha addition.
3 tablespoons fish sauce, plus more to taste
Three Crabs or Red Boat brands are worth it for clean flavor. Soy sauce or coconut aminos work for a vegetarian version.
3 tablespoons fresh lime juice (about 2 limes)
Add off the heat; cooking makes lime juice taste bitter. Lime juice is not a good substitute for lemongrass here, so use both.
1 teaspoon granulated sugar
Balances the sour and salty notes. Palm sugar is traditional; brown sugar is a fine stand-in.
1/4 cup chopped fresh cilantro and 2 sliced scallions, for serving
Stir in at the end so they stay bright green. Thai basil is a fragrant alternative.
Tips & Tricks
Do not boil the coconut milk
keep the slow cooker on Low and add coconut milk in the last 30 minutes if your model runs hot, or the fat can split and look grainy.
Fish out the aromatics
lemongrass, galangal and lime leaves are flavoring agents, not food. Use a slotted spoon to remove the big pieces before serving so every bowl is easy to eat.
Season at the end, not the start
fish sauce and lime juice added after the heat is off taste brighter and let you adjust to your brand of broth, which varies a lot in salt.
Pro Tips
Step-by-Step Instructions
1. Layer the aromatics
Add the chicken broth, lemongrass, galangal, torn lime leaves and sugar to a 6-quart slow cooker. Stir once so the aromatics are submerged and can infuse the liquid.
2. Add chicken and vegetables
Nestle the chicken thighs, mushrooms and bell pepper into the broth. They should be mostly submerged; push them down gently with a spoon if needed.
3. Cook on low
Cover and cook on Low for 3 hours, until the chicken registers 165F (74C) on an instant-read thermometer and shreds easily with a fork. On High, check at 2 hours.
4. Skim and remove aromatics
Lift out the lemongrass, galangal and lime leaves with tongs or a slotted spoon and discard. Skim any foam from the surface with a spoon so the broth looks clear.
5. Stir in coconut milk
Shake the coconut milk cans well, then pour both into the cooker and stir. Cover and cook on Low for 15 minutes, until the broth is hot and steaming but not bubbling hard at the edges.
6. Season off the heat
Turn the cooker off. Stir in the fish sauce, lime juice and a pinch of salt, then taste: the broth should be sour, salty and slightly sweet all at once. Adjust with more lime or fish sauce one teaspoon at a time.
7. Serve
Ladle into bowls, making sure each gets chicken and vegetables, and top with cilantro and scallions. Serve with steamed jasmine rice on the side for soaking up the broth.
Delicious Variations
Shrimp tom kha
swap the chicken for 1 pound peeled shrimp added in the last 20 minutes on Low, until they curl and turn opaque pink.
Vegetarian tom kha
use vegetable broth, soy sauce instead of fish sauce, and add 14 oz firm tofu cubes in the last 30 minutes.
Extra-hearty tom kha
add 1 cup cooked rice noodles to the bowls before ladling in the soup for a one-bowl meal.
How to Store Slow Cooker Tom Kha Soup (Thai Coconut Chicken Soup)
Refrigerator
Store in an airtight container in the refrigerator for up to 4 days; the coconut fat may solidify when cold, which is normal.
Freezer
Freeze the soup without the cilantro and scallions for up to 2 months in portion containers; leave 1 inch of headspace for expansion.
Reheating
Reheat gently on the stovetop over medium-low heat (about 250F/121C) for 5 to 7 minutes, stirring, until steaming; do not boil or the coconut milk may split. Add a squeeze of fresh lime after reheating.
Frequently Asked Questions
Q: Can I put raw chicken in a slow cooker for soup?
Yes, raw chicken thighs can go straight into the slow cooker with the broth and will safely reach 165F (74C) during the cook. Cut them into even 1-inch pieces so they cook at the same rate as the vegetables.
Q: Why did my tom kha soup curdle?
Coconut milk curdles when it boils or cooks too long at high heat. Add it in the last 15 to 30 minutes on Low and keep the broth at a gentle steam rather than a rolling boil.
Q: What does tom kha soup taste like?
Tom kha is creamy and lightly sweet from coconut milk, with a sour lime finish and a floral hit from lemongrass and lime leaves. It is milder and richer than tom yum, which is a clear, spicy-sour broth.
Q: Can I make tom kha soup without lemongrass or galangal?
Yes, use lemon zest and fresh ginger as stand-ins, though the flavor will be less floral. Add 2 wide strips of lemon zest and a 2-inch piece of sliced ginger with the broth, then finish with lime juice as usual.
Q: Is tom kha soup gluten-free and dairy-free?
Tom kha is naturally dairy-free because the creaminess comes from coconut milk. Check your fish sauce label for wheat, or use a gluten-free brand or coconut aminos to keep the whole pot gluten-free.
If you make this slow cooker tom kha soup, I want to hear how you tweaked it, whether that is extra chili, shrimp instead of chicken or a squeeze of lime at the table. Leave a comment and a rating below, and pin the recipe for your next cozy night in.
Slow Cooker Tom Kha Soup (Thai Coconut Chicken Soup)
This slow cooker tom kha soup simmers chicken in creamy coconut broth with lemongrass, lime and ginger for a cozy Thai dinner you set and forget.
🧂 Ingredients
- 1 1/2 pounds (680g) boneless, skinless chicken thighs, cut into 1-inch pieces
- 2 cans (13.5 oz / 400ml each) full-fat coconut milk
- 4 cups (960ml) low-sodium chicken broth
- 3 stalks lemongrass, outer leaves removed, cut into 2-inch lengths and smashed
- 1 piece (2-inch) fresh galangal, sliced thin
- 6 makrut lime leaves, torn
- 8 oz (225g) cremini mushrooms, quartered
- 1 medium red bell pepper, sliced into thin strips
- 3 tablespoons fish sauce, plus more to taste
- 3 tablespoons fresh lime juice (about 2 limes)
- 1 teaspoon granulated sugar
- 1/4 cup chopped fresh cilantro and 2 sliced scallions, for serving
📋 Instructions
- 1Layer the aromatics — Add the chicken broth, lemongrass, galangal, torn lime leaves and sugar to a 6-quart slow cooker. Stir once so the aromatics are submerged and can infuse the liquid.
- 2Add chicken and vegetables — Nestle the chicken thighs, mushrooms and bell pepper into the broth. They should be mostly submerged; push them down gently with a spoon if needed.
- 3Cook on low — Cover and cook on Low for 3 hours, until the chicken registers 165F (74C) on an instant-read thermometer and shreds easily with a fork. On High, check at 2 hours.
- 4Skim and remove aromatics — Lift out the lemongrass, galangal and lime leaves with tongs or a slotted spoon and discard. Skim any foam from the surface with a spoon so the broth looks clear.
- 5Stir in coconut milk — Shake the coconut milk cans well, then pour both into the cooker and stir. Cover and cook on Low for 15 minutes, until the broth is hot and steaming but not bubbling hard at the edges.
- 6Season off the heat — Turn the cooker off. Stir in the fish sauce, lime juice and a pinch of salt, then taste: the broth should be sour, salty and slightly sweet all at once. Adjust with more lime or fish sauce one teaspoon at a time.
- 7Serve — Ladle into bowls, making sure each gets chicken and vegetables, and top with cilantro and scallions. Serve with steamed jasmine rice on the side for soaking up the broth.
Editorial pen name used for practical articles and guides on Venture-Cook Simply Easy Recipes,.
