Chinese Beef with Broccoli

Cut partially frozen flank steak across the grain to make very thin 2 x 1-inch strips. In a small bowl, combine oyster sauce, water, sherry and cornstarch; stir until cornstarch is dissolved. Stir in crushed red pepper flakes and set aside. Heat a large nonstick skillet or wok over high heat. Add half the peanut oil and heat until very hot but not smoking. Add the beef and stir-fry until browned, about 2 minutes. Remove beef from wok with a slotted spoon and set aside. Heat the same skillet or wok over medium-high heat. Add remaining peanut oil and stir-fry ginger and garlic for 30 seconds. Add broccoli and stir-fry for 3 minutes. Turn heat to high and stir in red bell pepper, celery and green onion; continue to stir-fry for an additional 3 minutes. Stir in beef and reserved oyster sauce. Stir constantly until mixture thickens, about 2 minutes. Serve immediately garnished with cilantro.