Take the leg of lamb out of the refrigerator 3 hours before roasting. One hour before putting it in the oven, tuck several slivers of garlic into the meat. Rub it with salt and pepper. Preheat the oven for 15 minutes on maximum heat. Place the lamb on the rack of the roasting pan Sear the roast for 15 minutes, then lower the heat to medium (350 F). Halfway through the cooking, add 1/2 cup of water into the roasting pan. Check the lamb by inserting a trussing needle down to the bone, the tip should come out hot. Turn the oven off, leave to rest for 5 minutes. Slice the leg of lamb, retrieving the juice. Gradually add the butter, cut into small pieces, to the roasting pan and the meat juices, serve in a warmed sauceboat.
