Bring broth to a boiling medium sauce pan. Combine cornstarch and water in a small bowl. Set aside. Heat oil in wok over high heat. Add beef. Stir fry until no longer pink, breaking larger pieces with a wooden spoon. Add garlic and Chinese cabbage. Stir fry about 1 minute. Reduce heat and add broth mixture; stir until thickened. Add tofu; gently stir until heated, about 1 minute. Spoon tofu mixture over rice and garnish with green onions. Serves 4.
