In a resealable plastic bag or shallow glass container, combine the first five ingredients and mix well. Reserve 1/2 cup for basting and refrigerate. Add beef to remaining marinade; turn to coat. Seal bag or cover container; refrigerate for 1 hour, turning occasionally. Drain and discard the marinade.
On metal or soaked wooden skewers, alternate beef, tomatoes, mushrooms, green peppers and onions. Grill, uncovered, over medium heat for 3 minutes on each side. Baste with reserved marinade. Continue turning and basting for 8-10 minutes or until meat reaches desired doneness. Serve meat and vegetables over rice if desired.