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.
Place the lamb in the oven. For cooking time allow 30 minutes per 500g. Cover the lamb with foil after 20 minutes to avoid it becoming too brown, then uncover for the final 20 minutes of cooking. Top up the water a little as the lamb cooks to avoid the lamb drying out.