Place raw potato chips in a large bowl and cover with cold water. Set aside for 30 minutes to soak.
Line a large tray with paper towel. Drain the chips and arrange on the lined tray. Pat dry with paper towel (the chips need to be very dry).
Place the chips in a bowl and sprinkle with cornflour. Use your hands to rub the chips until the cornflour is lightly coating the outside. Preheat an air fryer at 200°C for 3 minutes. In batches, place the chips in a single layer in the basket. Spray with oil spray. Reduce the air fryer temperature to 190°C and cook, shaking the basket every 5 minutes, for 15-20 minutes or until golden.
Sprinkle your crispy chips with sea salt and serve immediately with tomato sauce, if desired.