If oysters are large, cut into bite-size pieces. In 2-quart saucepan, bring 2 cups water and salt to a boil. Add oysters. Turn off heat and let stand 30 seconds. Drain, rinse under cold running water and drain again. Combine chicken broth, sherry, oyster sauce, remaining 1 tablespoon water, cornstarch and sugar in small bowl; mix well and set aside. Heat 1 tablespoon oil in wok or large skillet over high heat. Add ginger and yellow onion; stir-fry 1 minute. Add green onions; stir-fry 30 seconds. Remove and set aside. Heat remaining 1 tablespoon oil in wok. Add blanched oysters and stir-fry 2 minutes. Return ginger and onions to wok. Stir cornstarch mixture and add to wok. Cook and stir until sauce boils and thickens.