Cut meat across the grain into thin strips, 1 1/2-inches long. Combine 1/2 tablespoon of the soy sauce, vinegar and egg white in medium bowl; beat lightly with fork until foamy. Mix in meat. Cover and let stand 1 hour, stirring occasionally. Cut celery into 1/2-inch diagonal slices. Combine celery, 1 cup of the water and the salt in saucepan. Cook over medium high heat until boiling. Boil 3 minutes. Drain celery. Heat 2 tablespoons of the oil in wok over high heat. Drain meat and add to wok. Stir-fry until meat is brown, about 5 minutes. Remove meat from wok. Add remaining 1 tablespoon oil to wok. Add celery, onions, ginger and garlic. Stir-fry 1 minute. Return meat to wok; mix well. Combine remaining 1/2 cup water, 1 1/2 tablespoon soy sauce, the sherry, cornstarch and oyster sauce. Pour over meat-vegetable mixture. Cook and stir until liquid boils and thickens.