Zest from 1 lemon mixed with 1/4 cup chopped italian parsley to garnish your sliced lamb with when serving

Take the leg of lamb out of the refrigerator about an hour before cooking so it comes closer to room temperature. Set the lamb in a rack inside a roasting pan. Drizzle with olive oil and rub all over into the fat and meat. Season generously all over with salt and pepper. Position the lamb so that it is fat-side down

Arrange an oven rack so that the top of the lamb is a few inches from the broiler element. Heat the broiler. Broil until the surface of the lamb looks seared and browned, about 5 minutes. 

Flip the leg over and put back under the broiler until the other side is seared, about 5 minutes more. Take the lamb out of the oven. Turn off the broiler and set the oven temperature to 325 degrees.

Reposition the oven rack to the middle of the oven. Rub the top of the lamb with the garlic and rosemary. 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.

Uncover the lamb and temp with an instant-read thermometer in the thickest part not touching bone. The lamb is ready when the temperature is 135 degrees which will be rare to medium rare, but it will continue to cook as it rests. Let the lamb rest at least 15 minutes before carving. Sprinkle the lemon zest parsley mixture on the sliced lamb and serve mint jelly on the side.