Carne asada barbecue

For the marinade:
1 cup lime juice
1/2 cup vegetable juice cocktail
1/4 cup chopped onion
1 tablespoon snipped fresh parsley or 1 teaspoon dried parsley flakes
2 cloves garlic, minced
1/2 teaspoon salt
1/4 teaspoon pepper
1 beef flank steak, about 1-1/2-pounds
2 sweet red or green peppers, cut into thin strips
1 large onion, thinly sliced
1 tablespoon butter
12 8-inch flour tortillas
3/4 cup salsa
3/4 cup prepared guacamole

1. To make the marinade: In a medium bowl whisk together all marinade ingredients.
2. Place steak in a resealable plastic bag set into a shallow dish. Pour marinade over steak; close bag. Marinate in the refrigerator 3 to 4 hours, turning bag occasionally to distribute marinade.
3. Meanwhile, cut an 18-inch square of heavy-duty aluminum foil. Place peppers and sliced onion in center of foil. Dot with butter. Bring up 2 opposite edges of foil and, leaving a little space for expansion of steam, tightly seal top, then each end.
4. Remove steak from marinade, reserving marinade. Place steak in center of cooking grate. Grill 10 to 15 minutes for rare or 15 to 19 minutes for medium, turning and brushing with reserved marinade once halfway through grilling time. Place foil packet of vegetables on the cooking grate beside steak during the last 10 minutes of grilling time.
5. Wrap tortillas in heavy-duty aluminum foil; place on cooking grate beside steak during the last 5 minutes of grilling time. Turn tortilla packet once halfway through grilling.
6. Slice steak diagonally across the grain into thin slices. Serve in tortillas with peppers and onions, salsa, and guacamole.