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.
1 Put the lamb in a roasting pan and season with salt and pepper, then drizzle over the oil. 2  Roast for 20 minutes, then reduce the oven temperature to 190c/375F/Gas Mark 5, and roast for a further hour (add an extra 20 minutes for well-done lamb). Roast for 20 minutes, then reduce the oven temperature to 190c/375F/Gas Mark 5, and roast for a further hour (add an extra 20 minutes for well-done lamb). 2  Remove from the oven and leave to rest in a warm place for 20 minutes before carving.