Peel and devein the shrimp. Rinse, dry on paper towels and cut into small pieces.
Rinse and dry the scallops. Chop into pieces the same size as the shrimp.
Place the cod in a food processor and process until a paste is formed. Scrape into a bowl and stir in the shrimp, scallops, chives, sherry, sesame oil, salt, and pepper.
Lightly beat the egg white and add to the seafood filling. Mix well, cover and leave to marinate in a cool place for 20 minutes.
Place 1 teaspoon of the seafood filling in the center of a wonton wrapper, then bring the corners together to meet at the top. Twist them together to enclose the filling. Do the same to the other wonton wrappers. Tie with a fresh chive, (optional).
Boil a large pan of water and drop in the wontons. When the water returns to a boil, lower the heat and simmer gently for 5 minutes (or until the wontons float to the surface).
Drain the wontons and divide them among four heated bowls.
Add a portion of lettuce to each bowl. Bring the fish stock to a boil. Ladle it on top of the lettuce and garnish each portion with cilantro leaves and chives.