The night before: In a food processor or blender, combine the chipotle peppers and 1-2 T of sauce, garlic, vinegar, water and cilantro. Spread half of marinade on bottom of 13 x 9 pan. Add flank steak and top with the remaining marinade.
Light a grill and pre-heat on high. Add steak and grill approximately 4 minutes per side for medium rare. Remove and allow to rest for 10 minutes before slicing diagonally against the grain (important in order for steak to be tender). Top with salsa. Serve with choice of sides (pictured-grilled plantains: slice, toss with olive oil, grill).