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.
Roast for 1 hour (this will give you a medium-rare cooked leg of lamb; roast lamb a further 30 minutes for well done). Carefully transfer the lamb to a carving plate or shallow tray, cover loosely with foil and set aside to rest. Increase oven temperature to 230Â°C or 210Â°C fan-force.oast for 1 hour (this will give you a medium-rare cooked leg of lamb; roast lamb a further 30 minutes for well done). Carefully transfer the lamb to a carving plate or shallow tray, cover loosely with foil and set aside to rest. Increase oven temperature to 230Â°C or 210Â°C fan-force.