Combine wine, lemon juice, instant marinade (Lawry’s Meat Marinade in Minutes works well and is found in the spice aisle or at the meat counter in most grocery stores), and peppercorns. Make 5 deep incisions in the leg with a sharp knife and insert a garlic clove deeply into each incision. In addition, pierce the meat with a fork liberally so the marinade will be able to penetrate into the meat. Place the leg of lamp in a pan and pour the marinade over the leg, turning so the marinade coats all sides. Return the marinated lamb to the refrigerator for a minimum of two hours or over night.
Before roasting, remove the leg of lamb from the refrigerator and allow it to come to room temperature. Pour the marinade from the pan the leg of lamb was marinating in and transfer into a sauce pan, heating to boil and then removing it from the heat. This will be used to baste the leg once roasting and also be used for the final reduction.
Place the leg in a roasting pan and place into a 400 degree oven, allowing 12 minutes per pound for rare. Baste approximately every 20 minutes with the marinade. To determine doneness, insert a meat thermometer into the leg, 140-145 for rare, 155-160 for medium. While it has been customary for lamb to be cooked in the United States to “well doneness”, French methods prefer to serve lamb rare to medium rare. Remember to check a few locations in the leg with the meat thermometer as thinner portions of the leg will roast through more quickly, and keep the thermometer away from the bone as it will give a higher reading.
Once the leg has reached the temperature of doneness desired, remove from the pan and allow to rest for 10 minutes before carving. Combine the pan juices with any remaining marinade and cook down until reduced by one third. Serve with the lamb.
As an alternative to the typical mint jelly, horseradish or horseradish sauce adds a nice complement to the flavor of this dish and can be served on the side.
This is an adaptation of a James Beard recipe.