Preheat the oven to 220 C, 200 Fan, Gas 7. Wash the potatoes and dry thoroughly then cut into 1.5 cm thick chips. Thoroughly pat the chips dry and spread over a large baking sheet in a single layer.
Drizzle the olive oil over the chips and sprinkle with the salt, pul biber and dried oregano. Use your hands to toss the chips in the oil and seasoning, then arrange them again in one layer and not touching one another.
Bake for 35-40 minutes, turning the chips halfway through the cooking time, until golden brown and crispy. Serve immediately .