In a bowl, combine 1 Tblsp. soy sauce, sherry, and 1/2 Tblsp. cornstarch. Stir in shrimp; cover, and marinate about 15 minutes. In another bowl, combine 1/4 cup stock with remaining soy sauce and cornstarch and the sugar. Heat 1 Tblsp. oil in a wok. Add shrimp and stir-fry about 3 minutes, until pink; transfer to a bowl. Heat remaining oil in wok. Add garlic and ginger and stir-fry about 30 seconds. Add celery, broccoli, and peppers, and stir-fry about 2 minutes. Stir in remaining stock. Reduce heat, cover, and cook about 3 minutes. Add pea pods, cover and cook about 2 minutes longer, until vegetables are tender. Stir in cornstarch mixture and cook, stirring constantly, about 1 minute. Stir in shrimp and cook 1 minute longer or just until heated through. Serve hot with steamed rice.