Mix together the vinegar, salt, pepper, garlic, onion, and olive oil in a large resealable bag until the salt has dissolved. Add lamb, toss until coated, and marinate in refrigerator for 2 hours.
Preheat an outdoor grill for medium-high heat.
Remove lamb from the marinade and leave any onions on that stick to the meat. Discard any remaining marinade. Wrap the exposed ends of the bones with aluminum foil to keep them from burning. Grill to desired doneness, about 3 minutes per side for medium. The chops may also be broiled in the oven about 5 minutes per side for medium.