1In resealable food-storage plastic bag, place beef and 6 tablespoons of the marinade. Seal bag; turn to coat beef with marinade. Refrigerate 20 minutes.
2Heat gas or charcoal grill. Remove beef from marinade; reserve marinade. On each of 4 (11-inch) metal skewers, thread bell pepper, beef and onion.
3Place kabobs on grill over medium-high heat; brush with reserved marinade. Cover grill; cook about 6 minutes, turning once, until beef is slightly pink when cut in center. Remove kabobs from grill to plate; let stand 5 minutes.
4Remove beef and vegetables from skewers; brush with remaining 2 tablespoons marinade. Serve with guacamole dip.