In small bowl whisk oil garlic rind and juice vinegar oregano salt and pepper Pour half into large storage bag add beef Seal refrigerate 1 to 2 hours Divide steak peppers onion and mushrooms into 6 equal portions Thread each portion onto large metal skewers Heat broiler Place skewers on large broiler-pan rack Brush with some of remaining marinade Broil 5 minutes Turn over brush with remaining marinade Broil 5 minutes Serve with rice