Enjoy this 30-minute authentic Thai lemongrass soup recipe with chicken and fresh Thai herbs. It’s a healthy version of tom yum without coconut milk, with a vegetarian option included!

Thai lemongrass soup simmering with herbs, chicken, vegetables, and red chilies.

Note: This recipe uses my homemade tom yum paste, but store-bought works just fine too. Feel free to swap the protein with shrimp or seafood if you prefer!

Thai lemongrass soup is a spicy, sour Thai soup made with lemongrass, galangal, kaffir lime leaves, and chili. It has a bold, aromatic flavor and is often cooked with chicken, shrimp, or vegetables. The broth is clear, light, and packed with spices.

Tom yum nam sai

The version of this Thai soup without coconut milk is called tom yum nam sai. The name refers to the clear version of tom yum, made without coconut milk or evaporated milk. It focuses purely on the hot, sour, and spicy flavors of the broth.

If you’re looking for a creamier, milder version with evaporated milk or coconut milk, try my tom yum gai.

Close-up of Thai lemongrass chicken soup with onions and chili in a clear broth, garnished with fresh cilantro.

Ingredient notes

You can find everything you need at Asian markets or Asian grocery stores. Head to the recipe card at the bottom of this post for all the measurements!

Thai lemongrass soup ingredients labeled: water, chicken, lemongrass, kaffir lime, tomato, galangal, salt, chili paste, coriander, flavor seasoning, tom yum paste.

Chicken – Use bone-in or boneless chicken thighs for rich flavor; chicken breast is a leaner alternative for a lighter soup.
Kaffir lime leaves – Add a bright, citrusy aroma; use fresh, frozen, or dried depending on availability.
Lemongrass – Infuses the tom yum lemongrass soup broth with a fresh citrus flavor; bruise the stalks to release more oils.
Galangal – A cousin of ginger, it brings a peppery, earthy note.
Cilantro
Rosdee seasoning powder – Rosdee is a Thai seasoning powder that adds umami and depth. You can find chicken, pork, or beef flavors, use the one that matches your dish or taste. A substitute is chicken stock bouillon powder, like Knorr.
Tom yum paste – Made with tamarind paste, palm sugar, fish sauce, and fresh herbs and spices.
Thai chili paste – Adds smoky heat and depth; made from dried chilies, shrimp paste, and garlic. Use my DIY chili paste or store-bought.
Large tomatoes – Cherry tomatoes work as a substitute.
Onion
Salt
Water

Vegetarian option: Use firm tofu instead of chicken and replace Rosdee with a mushroom or vegetable bouillon. Add different soup vegetables like mushrooms or bok choy.

How to make Thai lemongrass soup

Step 1: Place a pot over medium heat and add water, kaffir lime leaves, lemongrass, galangal, rosdee seasoning powder, salt, tom yum paste, chili paste, and sliced onion. Stir everything together and bring it to a boil.

Cooking process of Thai lemongrass in a soup with a spicy clear broth.

Step 2: Once the broth is boiling, add the sliced tomatoes and chicken. Let it simmer over medium heat until the chicken is fully cooked, and the flavors have blended.

Final stage of Thai lemongrass soup cooking process.

Step 3: Turn off the heat and garnish with fresh cilantro. Serve hot and enjoy while the soup is still fragrant and steamy.

How to use lemongrass in soup

How to prepare lemongrass for soup: Rinse the stalks under cold water and peel off the dry outer layers to reveal the tender, pale center.

How to cut it: Slice the stalk diagonally into 2–3 inch pieces and gently bruise them with the back of a knife to release the flavor. You can also thinly slice the tender inner part if you like to eat it.

When to add:
Add lemongrass early in the cooking process, when you first build the broth, so it has time to infuse the soup with flavor.

How much to use:
Use 1 to 2 stalks per pot of soup, depending on your taste and the size of the batch.

Lemongrass plant with long, thin green leaves growing outdoors in natural sunlight.

Storage and reheating tips

Refrigerate: Let the soup cool completely, then store it in an airtight container in the fridge for up to 3 days.
Freeze: Freeze without the fresh herbs for best texture. Store in a freezer-safe container for up to 2 months.
Reheat: Warm gently on the stovetop over medium heat until hot.

Authentic Thai soup recipes

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Praew

Thai food blogger

Hi, I’m Praew! I was born in Isan, Northeastern Thailand, where I started helping my grandmother cook from a young age. When I was six, I moved to Belgium and later spent my years working in Thai takeout restaurants. I even ran my own Thai restaurant there! Now I'm back in Thailand, sharing everything I’ve learned over a lifetime of cooking Thai food on this blog!