Mix the cornflour, salt, pepper, and Chinese five spice together in a large bowl.
Add the chicken and toss together to thoroughly coat each piece.
Arrange the coated chicken in the air fryer basket in a single layer (cook in two batches if necessary).
Squirt the chicken with spray oil and air fry at 200C/400F for 20 minutes, shaking twice during cooking.
Remove the chicken from the air fryer and place it in a bowl.
Add the onion, garlic salt, and black pepper to the air fryer basket and toss together.
Spray with spray oil and air fry for 5 minutes at 200C/400F.
Add the chopped chillies, toss, and air fry for a further 2 minutes.
Then add the spring onions and the chicken. Toss together and fry for a further 1-2 minutes, until the chicken is hot.