Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
     1/2  pound         small fresh shrimp shelled -- (shells reserved)
                        -- an
   2      quarts        chicken stock
   2                    green serrano chilies -- seeded and chopped
   1      teaspoon      salt
                        zest of one lime
   4                    kaffir lime leaves
   3                    lemon grass stalks, cut -into 1-inch
                        pieces
     1/2  pound         scallops
   2      tablespoons   fish sauce
                        juice of 3 limes
   3      tablespoons   fresh -cilantro, chopped
   1                    red serrano chili, seeded -and slivered
   6                    shiitake mushrooms, sliced
   2                    green onions, sliced -julienne

Preparation:

Combine shrimp shells with stock, chilies, salt, lime, zest, lime leaves and lemongrass stalks in heavy non-aluminum pot. Bring to a boil, reduce heat, cover and simmer for 20 to 20 minutes. Strain. Return liquid to pot and place over medium-high heat and bring to a boil. Add shrimp and scallops and cook for 1 minute. Stir in fish sauce and juice of limes. Add chopped cilantro, slivered red chili and shiitake slices, and green onions. Stir and pour into a tureen or ladle into individual bowls.