For marinade, in a bowl whisk together garlic, jalapeno peppers, olive oil, lime juice, mustard, and salt.

Trim fat from meat. With a sharp knife score meat on both sides at 1-inch intervals in diamond pattern. Place meat in a self-sealing plastic bag set in a shallow dish. Pour marinade over meat; seal bag. Marinate in refrigerator for 4 to 24 hours.

Heat a nonstick or well-seasoned grill pan on stovetop over medium heat. Drain meat; discard marinade. Place meat in hot pan. Cook for 14 to 16 minutes or until steak is medium, turning once halfway through grilling. Carve steak diagonally across the grain into thin slices.

Meanwhile, spread one side of each toast slice with mayonnaise. Place steak, onions, cheese, and cilantro on half the toast slices. Top with remaining slices. Serve with lime wedges. Makes 6 servings.

For tabletop grill: Preheat grill according to manufacturer's directions. Place steak on grill rack. If using a covered grill, close lid. Grill until steak is desired doneness. For covered grill, allow 7 to 9 minutes. (For open grill, allow 12 to 14 minutes for medium, turning once halfway through grilling.) Thinly slice steak diagonally across the grain. Continue as directed in Step 4 above.

To toast bread in a grill pan or an open grill, place on grill rack and allow 1 to 2 minutes per side. (Instead of a covered grill, use a toaster.)