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 2 hours.
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.
Heat 2 tablespoons of the oil in wok over high heat.
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;
Combine remaining 1/2 cup water, 1 1/2 tablespoons
soy sauce, the sherry, cornstarch and oyster sauce. Pour over meat-vegetable
mixture. Cook and stir until liquid boils and thickens.