Trim fat from steaks. For rub, in a small bowl combine habanero pepper, sage, and salt. Wearing plastic or rubber gloves, sprinkle mixture evenly over both sides of each steak; rub in with your fingers. If desired, cover and marinate in the refrigerator for up to 24 hours.
Prepare Lime and Sweet Onion Salsa. Cover and chill until ready to serve.
For a charcoal grill, grill steaks on the rack of an uncovered grill directly over medium coals for 10 to 12 minutes for medium-rare (145 degrees F) or 12 to 15 minutes for medium (160 degrees F), turning once halfway through grilling. (For a gas grill, preheat grill. Reduce heat to medium. Place steaks on grill rack over heat. Cover and grill as above.) Serve steaks with salsa.
Lime and Sweet Onion Salsa
Peel and section limes; chop lime segments. In a medium bowl stir together limes, onion, cilantro, sugar, and salt.