Preheat the oven to 200 (fan). Cut the potatoes into medium sized chunky chips. Place them on a tray and pat them using kitchen towel, to remove any excess water. Place in a bowl and season really well with cracked black pepper and salt. Spray liberally in oil and using your hands toss them together until coated well. Spread out on a wire baking rack (you can get ones especially for chips but if you don't have one a regular rack placed over a baking sheet will do).