Preheat the oven to 230°C. Place two baking trays in the oven to heat.
Cut the potatoes lengthways into 1-cm slices, then cut the slices lengthways into 1-cm strips. In a large bowl, combine the oil and pepper. Add the potatoes and toss well so that they are evenly coated.
Spread out the potatoes in a single layer on the hot baking trays. Return to the oven and bake, turning once, for 30–35 minutes or until browned, crisp and cooked through.