A rack is a connected series of rib chops. For some reason, home cooks regard racks of lamb as too fancy to grill—which couldn't be farther from the truth. A rack lends itself to grilling as readily as do separate chops—and it looks magnificent when lifted from the grill, perfectly browned and just a little crusty.
Trim the lamb, if necessary, and rub both sides of the rack with olive oil. Sprinkle with rosemary and pepper, rubbing them into the meatiest parts of the racks.
Prepare a charcoal or gas grill. Lightly spray the grill rack with vegetable oil cooking spray. The coals should be moderately hot to hot.
Grill the racks, meat side down, for 4 or 5 minutes, or until the temperature of the meatiest part reaches 100°F. Move the racks to the edge of the grill, away from the hottest part of the fire, and cook, covered, for 15 to 20 minutes longer, or until the temperature reaches 140°F for rare meat. Remove the racks from the grill and let them rest for five minutes before cutting between the ribs into individual chops.