Slice steak across the grain into 1/4"-1/2" strips and marinate for at least four hours, or overnight if desired. Remove meat from the marinade and discard the marinade. In a sauté pan, sauté beef, onion and bell pepper over medium heat until beef is browned and onion and bell pepper are tender. Stir in wedged tomatoes and sauté for five minutes more. Serve immediately with warm flour tortillas, grated cheese, sour cream, salsa and guacamole. Serves 4-6