Combine the rosemary, garlic, olive oil, salt and pepper in a bowl. (If desired, add the optional lemon and mustard)
Pour the marinade over the lamb chops and then rub it in to make sure the chops are covered completely.
Cover and let the lamb chops marinate in the refrigerator for as little as 1 hour, or as long as overnight.
Grill the lamb chops over medium-high heat on a preheated grill for 5 to 7 minutes per side, or until the internal temperature reads 135 degrees F.
Once done, allow the lamb chops to rest on a plate covered with aluminum foil for at least 5 minutes before serving.
Serve the grilled lamb chops with your choice of vegetable and starch.