Pour the oil into a large roasting pan, tilt the pan to distribute the oil, and place in the oven for 5 to 7 minutes, until the oil is smoking hot. Transfer the potatoes carefully into the oil, toss them lightly to coat each potato with the hot oil, and spread in one layer. Lower the oven temperature to 350 degrees F. Roast for 45 minutes to 1 hour, turning the potatoes occasionally with tongs, until very browned and crisp on the outside and tender and creamy inside.