Sprinkle the lamb liberally with the salt and pepper on both sides. Pour a thin layer of vegetable oil into a large skillet and place over high heat until the oil begins to smoke, 1 to 2 minutes. Working in batches, place the racks into the skillet. Sear for 1 minute per side, remove and put on a baking sheet. Put the lamb into the oven and roast until medium rare, about 15 to 18 minutes. Remove from the oven and let rest 5 minutes before slicing. Using a sharp knife, cut each rack in half. Serve immediately, half a rack per person.