Heat oil in wok over moderately high heat for 30 seconds. Add steak, and fry until no longer pink. Remove and place on paper towel to absorb grease. Add onion and green pepper to wok, and fry for one minute. Mix in mushrooms and herbs, and fry for 2-3 minutes. Raise heat to high and stir in white wine, and boil uncovered for one minute. Add beef broth and simmer, covered, for 3-4 minutes. Mix cornstarch and water to a smooth paste, and blend in. Stir until thickened, add beef, and cook for another minute.