Thai Lemon Soup with Chicken, Lemongrass, and Coconut

Thai lemon soup is a bright, gently creamy chicken soup flavored with lemongrass, galangal, makrut lime leaves, mushrooms, and fresh lemon juice. It is a Thai-inspired variation rather than a single traditional formula: lemon stands in for the lime more commonly used in Thai soups, while coconut milk softens the broth and makes it satisfying enough to serve as a meal.

Ingredients

1 tablespoon (15 ml) neutral oil, such as canola or sunflower oil
2 stalks lemongrass, about 6 ounces (170 g) total, tough outer leaves removed and lower sections bruised
1 tablespoon (15 g) thinly sliced fresh galangal; use fresh ginger if galangal is unavailable, knowing ginger tastes warmer and less piney
4 makrut lime leaves, lightly torn; substitute 1 teaspoon finely grated lime zest for a less floral aroma
1–2 Thai bird’s-eye chilies, lightly bruised, or ½ teaspoon red pepper flakes; adjust to taste
6 cups (1.4 L) low-sodium chicken broth
1 pound (450 g) boneless, skinless chicken breast, cut into thin bite-size strips
8 ounces (225 g) cremini or white mushrooms, sliced
1 cup (240 ml) unsweetened coconut milk, well shaken
¼ cup (60 ml) freshly squeezed lemon juice, plus more to finish
1 teaspoon finely grated lemon zest
2 tablespoons (30 ml) fish sauce
1 teaspoon (4 g) granulated sugar, or palm sugar if available
½ teaspoon fine salt, plus more as needed; the broth and fish sauce may already be salty
½ cup (12 g) loosely packed Thai basil leaves, or regular basil if needed
2 scallions, thinly sliced, for garnish
1 small lemon, cut into wedges, for serving

Instructions

Prepare the aromatics before heating the pot. Trim the dry tops from the lemongrass, then cut the tender lower portions into 3-inch (7.5 cm) pieces and bruise them with the flat side of a knife. Bruising helps release their fragrance without leaving tiny fibrous bits throughout the soup. Slice the galangal, tear the makrut lime leaves, and lightly crack the chilies. If you want a mild broth, leave the chilies whole; split them for more heat.
Warm the oil in a large, heavy saucepan or soup pot over medium heat. Add the lemongrass, galangal, lime leaves, and chilies. Cook for about 1 minute, stirring, just until fragrant. Do not brown the aromatics: scorching the delicate leaves or chili can make the broth taste bitter.
Pour in the chicken broth and bring it to a gentle boil. Lower the heat so the liquid simmers steadily, then cook uncovered for 10 minutes. This gives the broth time to take on the citrusy, herbal flavor. Keep it at a simmer rather than a rolling boil, which can make the finished soup cloudy and evaporate the liquid too quickly.
Add the chicken strips and sliced mushrooms. Simmer gently for 6–8 minutes, stirring once or twice so the chicken cooks evenly. Check the thickest chicken pieces with a food thermometer; USDA FSIS lists 165°F (74°C) as the safe minimum internal temperature for poultry. If a piece has not reached that temperature, continue simmering and check again rather than relying on color alone.
Stir in the coconut milk, lemon juice, lemon zest, fish sauce, sugar, and salt. Keep the soup below a boil and cook for 2–3 minutes, until hot. A hard boil can cause coconut milk to look grainy or separate, so lower the heat if bubbles become vigorous. Taste a spoonful before adding more salt, since fish sauce contributes plenty of seasoning.
Turn off the heat and stir in the Thai basil. Let the soup sit for 1 minute, then taste it again. Add extra lemon juice for a sharper citrus finish, a little more fish sauce for savory depth, or a splash of broth if it tastes too concentrated. Remove the lemongrass, galangal, and lime leaves before ladling; they are flavoring ingredients, not pleasant to chew.
Divide the chicken, mushrooms, and broth among four warm bowls. Scatter scallions over the top and serve with lemon wedges so each person can adjust the acidity. If the soup will be served with rice or noodles, keep them separate until serving so they do not absorb all the broth.

Tips

Use lemon at the end as well as in the pot. A little juice stirred in just before serving gives the soup a fresher aroma than adding all the citrus early. Lemon varies in acidity, so begin with the listed amount and adjust after tasting.
Choose substitutions with the flavor in mind. Galangal is sharper and more resinous than ginger, and makrut lime leaves have a distinctive floral citrus scent. Ginger and lime zest work when those ingredients are hard to find, but the result will be less specifically Thai in aroma. Bottled lemon juice can taste flat; fresh juice is preferable here.
Control the heat gently. Thai bird’s-eye chilies vary considerably in strength. Keep them whole for a lightly perfumed broth, or slice one for more heat. You can also serve chili flakes at the table, which lets everyone season their own bowl.
Keep the aromatics large enough to remove. Cut lemongrass into sturdy pieces and slice galangal into coins rather than mincing either one. Their woody texture is unpleasant in a spoonful, but larger pieces are easy to fish out before serving.

Serving Suggestions

Serve the soup hot as a light main course, with steamed jasmine rice on the side to soak up the lemony coconut broth. For a heartier bowl, spoon cooked rice into each serving bowl before adding soup; keeping rice separate in the pot prevents it from turning soft as the soup sits. Rice noodles also work well, especially if cooked separately according to their package directions and added just before serving.

A simple plate of sliced cucumber, herbs, or crisp vegetables makes a refreshing contrast to the warm broth. Set out lemon wedges, extra Thai basil, and a small dish of sliced chilies so diners can adjust the flavors. The soup already contains fish sauce, so a salty side dish is usually unnecessary; plain rice is a useful balance if the broth tastes especially tangy or spicy.

Variations

Make it without coconut milk: Leave out the coconut milk and use an additional 1 cup (240 ml) chicken broth. The soup will be clearer and lighter, closer in style to a hot-and-sour Thai soup, though lemon still gives it a different citrus profile from the lime often used in tom yum. Taste and adjust the fish sauce and lemon after the broth is hot.

Use shrimp instead of chicken: Replace the chicken with 1 pound (450 g) peeled, deveined shrimp. Add the shrimp after the mushrooms and simmer just until opaque and cooked through; check that they reach 145°F (63°C) with a food thermometer. Shrimp cook quickly, so avoid leaving them in the pot while the broth continues to simmer.

Make it vegetarian: Use vegetable broth, replace the fish sauce with 1 tablespoon (15 ml) soy sauce, and add 8 ounces (225 g) cubed firm tofu in place of the chicken. Soy sauce is not a perfect flavor match for fish sauce, but it adds useful savory depth. Check that the broth and any other packaged ingredients are vegetarian if that matters for your meal.

Add vegetables or noodles: Thinly sliced bell pepper, baby corn, or a handful of spinach can go in with the mushrooms; add delicate spinach near the end so it just wilts. For noodles, cook about 6 ounces (170 g) dried rice noodles separately, drain, and divide among bowls. The extra ingredients make a more substantial serving, but avoid packing the pot so tightly that there is not enough broth to cover everything.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking in a covered, shallow container. For best quality, store the soup for 3–4 days in the refrigerator. If you expect leftovers, consider storing cooked rice or noodles separately; they continue to absorb liquid and can become mushy when kept in the broth.

Reheat only the amount you plan to eat in a saucepan over medium-low heat, stirring occasionally until steaming throughout. Leftovers should reach 165°F (74°C) when checked with a food thermometer. Avoid a vigorous boil, which can separate the coconut milk, and add a squeeze of fresh lemon after reheating if the citrus flavor has mellowed. You can freeze the soup in a freezer-safe container for up to 2 months, though coconut milk may separate slightly after thawing; stir gently while reheating. Thaw overnight in the refrigerator rather than on the counter.

Frequently Asked Questions

Is Thai lemon soup the same as tom yum?
Not exactly. Tom yum is a Thai hot-and-sour soup commonly flavored with ingredients such as lemongrass, galangal, and makrut lime leaves, with lime providing the sour note. This recipe borrows that aromatic direction but uses lemon and coconut milk, so it is best described as a Thai-inspired lemon soup rather than a definitive traditional tom yum recipe. Thai soups have regional and household variations, too.

Can I use bottled lemon juice?
You can, but fresh lemon juice and zest give the broth a brighter, more fragrant flavor. If bottled juice is what you have, start with about 3 tablespoons (45 ml), taste the finished soup, and add more gradually. Bottled juice can be sharper or less aromatic depending on the product, so the exact amount may differ.

How can I make the soup less spicy?
Use one whole chili, or omit it entirely, and do not cut or crush it. If the soup is already too hot, stir in a little extra coconut milk or broth and serve it with plain rice. Adding lemon alone will not remove the heat, and adding a lot of sugar can make the overall balance overly sweet.

Why did my coconut milk separate?
Coconut milk can separate when it is boiled hard, and some brands separate more readily than others. It is still usable if this happens; lower the heat and stir gently to bring the broth together as much as possible. For a smoother result next time, shake the can well and add the coconut milk near the end, heating it gently without a rolling boil.

Can I make the soup ahead?
Yes. You can prepare the broth with the aromatics earlier in the day, cool it promptly, and refrigerate it, then reheat and cook the chicken and mushrooms shortly before serving. Or make the complete soup and refrigerate it within 2 hours, following the storage and reheating guidance above. Fresh lemon and basil are best added or refreshed just before serving.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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