The first time I made Tom Kha, I was convinced it would take two hours and a specialty grocery run. It took 30 minutes and a trip to a regular grocery store. The lemongrass and kaffir lime leaves are sold at most Asian grocery stores and increasingly at larger supermarkets — they make this soup what it is, so don’t skip them.

Tom Kha is one of those dishes that’s naturally gluten-free and dairy-free without any substitutions. The coconut milk is the fat source, the fish sauce is the salt. It’s already ours.

Why it works

The broth is built in layers. The aromatics — lemongrass, galangal, lime leaves — infuse into the coconut milk over low heat, creating a fragrant base that commercial versions can’t replicate. The shrimp goes in at the very end and cooks in 2 minutes. Overcooking shrimp is the one thing that ruins this soup.

Fish sauce is the seasoning backbone and it’s almost always gluten-free. It’s fermented fish and salt — check your specific brand’s label, but most are safe. Tiparos and Megachef are reliably GF.

Ingredients

Broth:

• 1 can (13.5 oz) full-fat coconut milk
• 2 cups certified GF chicken or vegetable broth
• 2 stalks lemongrass, bruised and cut into 2-inch pieces
• 1 inch galangal or fresh ginger, sliced
• 4 kaffir lime leaves, torn (or 1 tsp lime zest)
• 2 Thai bird chilies, sliced (or ½ tsp chili flakes)
• 2 tablespoons fish sauce
• 1 tablespoon coconut or brown sugar
• 3 tablespoons fresh lime juice

Soup:

• 1 lb large shrimp, peeled and deveined
• 2 cups oyster or cremini mushrooms, sliced
• 1 tablespoon oil

To serve:

• Fresh cilantro, sliced green onions, lime wedges
• Jasmine rice or rice noodles (optional)

Instructions

1. Bruise the aromatics. Use the back of your knife to smash each lemongrass stalk — this releases the oils. You’re not cutting them fine, just bruising so the flavor infuses. Slice galangal or ginger into coins.

2. Build the broth. In a medium saucepan, combine coconut milk and broth over medium heat. Add lemongrass, galangal, kaffir lime leaves, and chilies. Bring to a gentle simmer (not a boil — high heat can break coconut milk). Simmer 10 minutes. The broth should be fragrant and slightly yellow.

3. Sauté the mushrooms. While the broth simmers, heat oil in a skillet over medium-high heat. Add mushrooms and cook without stirring for 3–4 minutes until golden. Season with a pinch of salt. Set aside.

4. Season the broth. Add fish sauce, sugar, and lime juice to the simmering broth. Taste — it should be balanced: salty, tangy, subtly sweet, and fragrant. Adjust with more fish sauce for salt, lime for acid, or sugar if too sharp.

5. Cook the shrimp. Add mushrooms to the broth. Add shrimp and cook 2 minutes, just until pink and curled. Pull immediately — overcooked shrimp turns rubbery.

6. Serve. Ladle into bowls. The lemongrass and galangal pieces are for flavor only — eat around them or remove before serving. Top with cilantro, green onions, and a squeeze of lime. Serve over rice or with rice noodles if you want a heartier meal.

Hannah’s note: This is a medium-spicy soup as written. If you’re not sure about the heat level, start with one chili and add more at the table. The lime juice at the end is what brightens the whole bowl — don’t skip it.

Tips & Substitutions

• No lemongrass? Add 1 teaspoon lemongrass paste (sold in tubes in most grocery stores) and 1 extra teaspoon lime zest. Not quite the same, but close.
• Vegetarian version: Use vegetable broth, skip the shrimp, and add tofu and more mushrooms. Replace fish sauce with tamari — the flavor profile shifts slightly but it’s still very good.
• Chicken instead of shrimp: Use thinly sliced chicken breast or thigh. Add at step 5 and cook until no longer pink, about 5–6 minutes.
• Make it heartier: Add a handful of baby spinach or sliced bok choy in the last minute of cooking.

Frequently asked questions

Is fish sauce gluten-free? Most fish sauces are GF — the ingredients are typically anchovies, salt, and water. But some brands add wheat, so check the label. Tiparos and Red Boat are both reliably gluten-free.

Where do I find kaffir lime leaves and galangal? Asian grocery stores carry both fresh. Larger supermarkets (Whole Foods, H-E-B, Wegmans) often have them frozen. Kaffir lime leaves also freeze well — buy a bag and keep it in your freezer.

Can I make this ahead? The broth (without shrimp) keeps 3 days refrigerated. Reheat gently and add fresh shrimp right before serving. Cooked shrimp in soup doesn’t reheat well.

What’s the difference between galangal and ginger? Galangal is more piney, citrusy, and slightly floral. Ginger is warmer and spicier. In this soup, galangal is traditional — use ginger as a substitute if you can’t find it, knowing the flavor will be warmer and less complex.