Soak the potatoes in just-boiled water for 30 mins, then drain and leave to air-dry for 5 mins. Heat the air fryer to 200C. Tip the potatoes into a bowl and drizzle over 1 tbsp of the oil and add 1/2 tsp each of salt and freshly ground black pepper. Mix to coat the potatoes all over, then tip into the air fryer basket and cook for 20-30 mins until crisp and golden.