Lamb is typically roasted to medium-rare or medium to maintain its flavor and tenderness. A bone-in roast requires 10-15 minutes more total cooking time than a boneless roast. After the lamb has finished cooking in the oven, it should be allowed to rest for 10-15 minutes, which allows the juices to settle (the lamb will continue to cook a little during this resting period). Lamb roasts should be marinated overnight, and removed from the refrigerator 1-2 hours before going into the oven. Always place your lamb roast on a rack in an open roasting pan with the fatty side up to allow the juices to drip through the meat. A meat thermometer should be inserted into the thickest part of the roast. A thermometer reading of 135 will be medium-rare (after resting), and a reading of 145 will be medium (after resting). There are two ways to roast a lamb properly. Roasting at a consistent low temperature will produce an even temperature throughout. This is good when all guests like their meat cooked to the same “done-ness”. Cooking at a high temperature for the first 20 minutes then reducing to a lower temperature for the remainder of the cooking time will result in the ends being cooked more than the center. This is good if some guests prefer their meat more well-done than others. Below are both styles of roasting.
Preheat oven to 325. Place 5 lb. bone-in marinated lamb roast fat side up on a rack in a roasting pan. Cook for about 20 minutes per pound (1 hour & 40 minutes) or until the meat thermometer reads 145 for a medium roast. Allow lamb to sit for 10-15 minutes before carving.
Preheat oven to 450. Place bone-in marinated lamb roast fat side up on a rack in a roasting pan. Bake at 450 for 20 minutes, then reduce heat to 400 and roast for 55-60 minutes or until the meat thermometer reads 145 for a medium roast. Allow lamb to sit for 10-15 minutes before carving.
Recipe courtesy of The Butcher Shoppe.