In general I prefer to cook meat on the bone. Whether I’m braising, roasting or grilling, the bone contributes rich flavor and also helps to keep the meat from drying out. For lamb I roast the shank end of half a leg, about 3 1/2 to 4 pounds to serve 4 to 6 people.
There are two ways to cook a bone-in leg of lamb. The first is low and slow, low cooking temperature for a long period. The meat is tender and falling off the bone once it’s done. The second is to roast the lamb at a higher temperature for a short period and cook the meat to medium-rare. I prefer the quicker roast and the texture of lamb served medium-rare.
Many recipes call to start the lamb in a very hot oven to sear the fat and then lower the temperature, or, finish the lamb at a higher temperature near the end of cooking to crisp the exterior. I remove the lamb from the refrigerator 1 hour before cooking to take the chill off and keep it simple by roasting at 375 F the entire time. At 375 F for 50 to 65 minutes the exterior crisps nicely and the lamb stays juicy. I like my lamb with just a hint of red so I cook it to 125 F then cover with foil once it’s out of the oven. The temperature of the meat continues to rise while it rests. You can let the lamb rest up to 45 minutes or even an hour while you prepare the rest of your meal.
To serve 8 to 10 people, buy a whole bone-in leg of lamb from your butcher, around 8 pounds. Double the recipe for the garlic rosemary mixture and let lamb sit at room temperature for 2 hours before cooking. The lamb will take closer to 1 hour and 45 minutes to 2 hours to cook but always use an instant read thermometer to determine when it’s actually done.
Roast Bone-In Leg of Lamb
serves 4 to 6
Ingredients
1 head garlic, about 10 to 12 cloves, peeled
4 large sprigs rosemary, leaves removed
zest of 1 lemon
Kosher salt
Freshly ground black pepper
1/4 cup extra virgin olive oil
3 1/2 to 4 pounds bone-in leg of lamb, preferably tied and fat scored
Place garlic cloves in a food processor fitted with a steel blade. Pulse until well minced. Scrape down sides of processor bowl with a rubber spatula. Add rosemary, lemon zest, 2 tablespoons salt and 2 teaspoons pepper and pulse until rosemary is well chopped and a thick paste forms. Scrape down sides of bowl down, again. With machine running add olive oil in a steady stream and process until combined.
Set lamb in a roasting pan and pat it dry with paper towels. Cover leg entirely with the garlic rosemary mixture. Refrigerate, uncovered, for 8 hours or overnight.
Take lamb out of refrigerator to come to room temperature 1 hour before roasting. Preheat oven to 375 F.
Roast lamb until an instant read thermometer inserted in the thickest part of the leg reads 125 F for medium rare, about 50 minutes to 1 hour and 5 minutes, or up to 1 hour 20 minutes for medium at 135 F.
Transfer lamb to a cutting board and tent with foil to rest for 20 to 30 minutes. Carve lamb into 1/2-inch thick slices, reserving any juices from the cutting board, and serve.
Carving a bone-in leg of lamb sounds daunting but it’s not difficult. Here’s a great step-by-step video tutorial from Mark Bittman.