Preheat the oven to 400°. In a medium skillet, heat 1 tablespoon of the oil until shimmering. Season the lamb with salt and pepper. Add the lamb to the skillet, fat side down, and cook over moderately high heat until richly browned, about 3 minutes. Turn the lamb fat side up and cook for 2 minutes longer. Transfer the skillet to the oven and roast the rack for about 20 minutes, until an instant-read thermometer inserted in the center of the meat registers 125° for medium-rare. Transfer the lamb to a carving board and let rest for 10 minutes.