Directions. 1  Preheat oven to 450 degrees. 2  Season lamb racks with salt and pepper; coat each evenly with 3 Tbsp pesto. 3  Roast on baking sheet until about 5 degrees less than desired doneness (about 20 min for medium). 4  Transfer lamb to clean platter; let rest 10 min before slicing.
Preheat the oven to 400 degrees F. Using your hands, rub the lamb all over with the lemon juice. Pat the garlic and rosemary evenly all over the surface of the meat. Season the meat with the salt and pepper and place the lamb in a roasting pan. Place the lamb in the oven and roast for 30 minutes.
Insert meat thermometer so tip is in thickest part of lamb (not resting in fat). Cook until the lamb roast reaches an internal temperature of 120 degrees F. Remove from oven, cover with aluminum foil, and let sit approximately 15 to 20 minutes. Remember, the lamb roast will continue to cook as it sets.nsert meat thermometer so tip is in thickest part of lamb (not resting in fat). Cook until the lamb roast reaches an internal temperature of 120 degrees F. Remove from oven, cover with aluminum foil, and let sit approximately 15 to 20 minutes. Remember, the lamb roast will continue to cook as it sets.