Put the oil in a roasting pan large enough to the potatoes to fit in a single layer. Put the pan in the oven and preheat the oven and pan with oil to 450F.
Cut the potatoes into french fry shapes and wipe the pieces with paper towels to remove any surface wetness.
Mix together the potato flour and the spices and coat the potatoes. This is most easily done by shaking in a gallon zippered plastic bag. Put the coated potatoes in a colander and toss to remove excess seasoned flour.
Place the coated potatoes in a single layer in the hot oil. Roast for a total of 30 minutes, flipping the potatoes at 10 minute intervals.
Remove the potatoes on a double layer of paper towels and blot with a third layer to remove any excess oil while the potatoes are still hot.