2-3 Thai chilies, crushed (adjust to heat preference)
1/4 cup fish sauce
1/4 cup fresh lime juice
1 tablespoon Thai chili paste (Nam Prik Pao) (optional, for color and depth)
1 cup straw mushrooms or button mushrooms, halved
1/2 cup cilantro, chopped, for garnish
1/4 cup Thai basil leaves (optional)
1/4 cup coconut milk (for creamy version only)
Instructions
Combine the broth, bruised lemongrass, sliced galangal, torn kaffir lime leaves, and crushed chilies in a medium pot. Bring the mixture to a boil over medium-high heat.
Reduce the heat and simmer for 10 minutes to infuse the broth with the aromatics.
Strain the broth to remove the lemongrass, galangal, and kaffir lime leaves, returning the liquid to the pot. Discard the solids.
Add the mushrooms and bring the broth back to a gentle simmer.
Add the shrimp and cook until they turn pink and opaque, about 2 to 3 minutes. Do not overcook.
Stir in the fish sauce and Thai chili paste (if using).
Remove the pot from the heat. Stir in the fresh lime juice.
For the Clear Version (Nam Sai): Serve immediately garnished with cilantro and basil.
For the Creamy Version (Nam Khon): Before serving, stir in the coconut milk gently until combined, then garnish.
Notes
For a Vegetarian Tom Yum, substitute vegetable broth and use firm tofu or mixed vegetables instead of shrimp. Replace fish sauce with soy sauce or vegetarian fish sauce substitute.
To make a Chicken Tom Yum, use sliced chicken breast instead of shrimp, adding it when you add the mushrooms.
Adjust the amount of lime juice and fish sauce at the end to balance the sour and salty flavors to your liking.