Gently tenderize steaks with a meat mallet. With a sharp knife, lightly score the meat on one side diagonally. Place steaks in a casserole dish, scored side up, and pour bourbon over them. Rub the brown sugar evenly over each steak. Marinate in refrigerator for 1 to 3 hours.
Preheat grill to high heat, and lightly oil grate.
Place the steaks on the hot grill, with the sugar side down. Let cook until sugar has caramelized, 3 to 5 minutes, then flip steaks, and finish cooking to desired doneness.