Slice potatoes into spirals using the medium grating attachment on a spiraliser, cutting the spirals with scissors after 4 or 5 rotations.
Soak potato spirals in a bowl of water for 20 minutes. Drain and rinse well. Pat potatoes dry with kitchen roll, removing as much moisture as possible.
Place potato spirals in a large resealable food bag. Add oil, salt and pepper; toss to coat.
Preheat an air fryer to 180 C.
Place half of the potato spirals in the fry basket and insert into the air fryer. Cook until golden, about 5 minutes.
Increase temperature to 200 C. Pull out the fry basket and toss curly fries using tongs. Return basket to the air fryer and continue cooking, tossing occasionally, until golden brown, 10 to 12 minutes.
Reduce temperature to 180 C and repeat with remaining potato spirals.