In a large bowl, add the lamb chops.
Add the chopped onion, white vinegar, olive oil, rosemary, salt, and black pepper. Toss to coat them well in the marinade.
Cover and refrigerate for at least 2 hours, or overnight for the best flavor.
Preheat a grill to medium-high heat and lightly oil the grates.
Remove the lamb chops from the marinade and shake off any excess onion before placing them on the grill.
Grill the lamb chops for 5 minutes per side, depending on thickness and desired doneness.
Transfer the grilled lamb chops to a platter and let them rest for 5 minutes before serving.Serve warm with tahini sauce and your favorite Mediterranean side dishes.