Combine marinade ingredients in a bowl. Add fish, shrimp and scallops; stir to coat. Let stand 10 minutes.
Bring stock and winter melon to a boil in a pot; reduce heat to simmer.
Stir in seafood; cook 2 minutes. Add ginger, green onion, mushrooms, bamboo shoots, peas, wine and white pepper; cook 1 minute. Add cornstarch solution; cook, stirring, until soup boils and thickens. Turn off heat. Add egg whites, stirring until they form threads. Serve in individual soup bowls.
Chef Yan has remained an active international food ambassador throughout his career. He roams the world representing different commercial and social concerns to entertain and educate the public, sharing with them his unique humor and strong passion for Chinese cooking.