How to Cook a Leg of Lamb Roast

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Lamb roast comes into its own as a traditional dish for Passover or Easter, but it makes a gamier alternative to pork and beef year-round. One of the more expensive joints to roast, lamb can be intimidating. Luckily, it is a relatively straightforward joint to master, bursting with its own flavor and not easy to overcook.

Choosing a Leg

Lamb leg is taken from animals less than a year old, in season from March through October. Most legs sold in supermarkets are butterflied with the bone removed, wrapped in an oven-proof netting to hold the meat in the shape of a leg. Since a lot of the flavor is in the bones, however, it is worth tracking down a bone-in leg. Usually these are just the upper thigh with the shank removed. Those with the shank attached are referred to as American legs. A 3-pound boneless leg should be enough for six people, allowing roughly half a pound of meat per serving. If buying lamb directly from the butcher, ask for some of the internal fat to be trimmed away. Although it contributes to the roast’s rich flavor, this is already quite a fatty joint, and too much can be overpowering.

Basic Preparation

Lamb has a strong flavor, and the meat is already quite tender, so marinating is not necessary. A complementary herb or spice rub will usually suffice. Pesto, for example, makes a great seasoning, as does an olive tapenade. If cooking with a boneless leg, pine nuts and feta can also be stuffed inside the butterflied meat before it is rolled. Other flavors that are robust enough to cope with lamb’s aroma are garlic and herbs. Score the leg’s surface with small incisions from the tip of a sharp knife and rub in a garlic and herb, such as rosemary, butter. If you must marinade, two to three hours is enough, as any longer can break down the texture. Try an Indian-themed marinade of yogurt and ginger, refrigerated in a resealable plastic bag. In all cases, avoid salting the leg before roasting, as this will draw out much-needed moisture.

Easy Roasting

Once seasoned, leg of lamb is a fuss-free joint to cook. Lay the joint on a rack in a roasting tray and sear it first for 15 minutes in an oven preheated to 450 degrees. Allowing 25 minutes’ roasting per pound, cook it subsequently at 325 degrees covered with aluminum foil. The only reliable measure of doneness is a cook’s thermometer inserted into the meat in the center, not the bone or fat. The USDA recommends a safe internal temperature of 145 degrees, but bear in mind the lamb will cook during resting and will appear pink even when safely cooked. For a rare cut, remove the joint from the oven at 120 degrees Fahrenheit, or 155 to 165 degrees for well done. Keep the leg covered and allow it to rest for 15 minutes at least.

Carving and Serving

Carving a leg of lamb requires a certain level of finesse with a long-bladed, flexible knife, since the servings are usually thin and delicate. Laying the joint on a cutting board, cut a few slices parallel to the bone, working from the outside to the center. This will create a flat surface. Turn the leg and rest it on the flat side; then slice with thin cuts perpendicular to the bone, all the way along its length. Next lay the knife flat and cut horizontally down the bone, liberating each slice at the base. For boneless legs, cut away the netting and slice vertically, a much easier process. Many restaurants serve lamb au jus, collecting the liquid in the roasting pan, spooning off any excess fat and fortifying with a glass of red wine. Heat this clear sauce on the stove top in a pan while the lamb is resting; then pour it over the cut slices.