In a bowl whisk together garlic, jalapeno peppers, olive oil, lime juice, mustard, and salt.
Trim fat from meat. With a knife score meat on both sides at 1-inch intervals in diamond pattern. Place meat in a zip-lock plastic bag placed in a shallow dish. Pour marinade over meat; seal bag. Marinate in refrigerator for 4-24 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 14-16 minutes or until steak is medium, turning once halfway through grilling. Carve steak diagonally across the grain into thin slices.
In a small bowl, mix mayonnaise with chipotle(or chile powder).
Meanwhile, spread one side of each toast slice with mayonnaise mixture. Place steak, onions, cheese, and cilantro on half the toast slices. Top with remaining slices. Serve with lime wedges.