Only instead of chicken, this recipe uses shrimp so is called Tom Kha Goong.  

Note that red curry paste, fish sauce and coconut milk are all easily available in most Nakumatts and Chandranas around the city and lemon grass is available at many green grocers, although sometimes sporadically.  I grow mine in the back yard- it’s dead easy to grow.

Ingredients
vegetable oil
2 tablespoons grated fresh ginger
1 stalk lemon grass, chopped finely
2 teaspoons red curry paste
4 cups chicken broth
3 tablespoons fish sauce
2 tablespoons light brown sugar
3 (13.5 ounce) cans coconut milk
1/2 pound fresh shiitake mushrooms, sliced
1 pound medium shrimp - peeled and deveined
2 tablespoons fresh lime juice
salt to taste
1/4 cup chopped fresh coriander (dhania)

Directions
Heat the oil in a large pot over medium heat. Stir in ginger, lemongrass, and curry paste. Slowly pour chicken broth over the mixture, stirring continually. Stir in fish sauce and brown sugar; simmer for 15 minutes. Stir in coconut milk and mushrooms; stir until the mushrooms are soft then add the shrimp and stir until no longer translucent (about 5 minutes). Stir in the lime juice. Season with salt. Garnish with coriander and serve with additional wedges of lime.