Heat grill. Wrap tortillas in foil; set aside. In small bowl, combine soy sauce, lime juice and garlic; mix well.
Thread beef, onion and bell pepper pieces onto four 8 to 10-inch metal skewers. Brush kabobs generously with soy sauce mixture.
When ready to grill, place kabobs on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 7 to 10 minutes or until beef is of desired doneness, brushing frequently with soy sauce mixture.
During last 5 minutes of cooking time, place tortilla packet on grill; heat until tortillas are warm, turning foil packet once.
To serve, remove cooked beef and vegetables from skewers; cut beef into bite-sized pieces. Serve beef and vegetables in warm tortillas. If desired, serve with cheese and sour cream.