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.
