Marinate beef slices for 30-60 minutes. Break broccole heads into 1 inch pieces and cut stems into thin slivers; set aside.
Heat 2 tbsp oil in wok until very hot, then stir-fry beef until it is medium rare. Remove and set aside. Heat 1 tbsp oil until very hot, then stir-fry broccoli 1 minute. Add 2 tbsp water, cover, and simmer 5 minutes or until the stems are tender. Add the beef and gravy mixture. Cook until the sauce thickens.