1 (5 to 7 pound)
bone-in leg of lamb
Freshly ground black pepper
Leaves from 3 fresh rosemary sprigs, chopped
Roasting pan, with rack
Sharp chef's knife or carving knife, for carving
Take the lamb out of the refrigerator an hour before cooking. Take the leg of lamb out of the refrigerator about an hour before cooking so it comes closer to room temperature. This promotes faster, more even cooking.
Rub the lamb with olive oil. Set the lamb in a rack inside a roasting pan. Drizzle with olive oil and rub into the fat and meat.
Season with salt and pepper. Sprinkle liberally all over with salt and pepper.
Heat the broiler. Arrange an oven rack so that the top of the meat is a few inches from the broiler element. Heat the broiler.
Broil for 5 minutes. Broil until the top of the lamb leg looks seared and browned, about 5 minutes.
Flip the lamb over and broil the other side. Flip the lamb over and put back under the broiler until the other side is seared, about 5 minutes more.
Top with garlic and rosemary. Take the lamb out of the oven. Turn off the broiler and set the oven temperature to 325°F. Reposition the oven rack to the middle of the oven. Flip the lamb leg over again and rub the top with the garlic and rosemary.
Cover the lamb loosely with foil. Tent the pan loosely with aluminum foil to keep the garlic and rosemary from burning. Put the lamb back in the oven and roast for 1 hour.
Remove the foil after an hour and take the temperature. Uncover the lamb and take its temperature with an instant-read thermometer in the thickest part not touching bone. The lamb is ready when the temperature is 135°F or above. At 135°F the lamb is cooked to rare, but it will continue cooking as it rests, so we recommend taking it out of the oven at 135° for medium-rare to medium. (Refer to the cooking chart above for general roasting times.)
If needed, continue cooking the lamb until done. If the lamb is not ready, continue cooking uncovered until it reaches your desired internal temperature, checking the temperature every 20 minutes.
Let the leg of lamb rest. Let the lamb rest for at least 15 minutes before carving.
Carve the lamb. Place the lamb on a cutting board. Turn it so the bone is parallel to the cutting board. Make perpendicular slices to the bone, angling straight down until your knife hits the bone.
Carve the meat off the bone. Cut the lamb off the bone by slicing through the bottom of the slices with your knife parallel to the bone.