Slice steak into 2 1/8-inch strips. Pour into bowl, season with pepper. Set aside.

In small bowl combine water, soy sauce, and cornstarch; mix well. Set aside.

In large wok or skillet, heat 2 Tbsp oil. Add onions, sauté until onions are tender. Add steak and brown until no longer pink. Add pepper and cook an additional 15-20 minutes. Add soy sauce mix, stir until thick. Serve over white rice.