Trim excess fat from the chicken thigh fillets and chop them into bite-sized pieces. Set aside.
Combine the cornflour, salt, pepper, garlic powder, and paprika in a mixing bowl.
Add the chicken pieces to the bowl and toss until each piece is evenly coated with the cornflour mixture.
Pour the oil over the coated chicken and stir well to make sure all pieces are sticky and well covered.
Arrange the coated chicken pieces in the air fryer basket and cook at 190C/375F for 15 to 18 minutes, shaking the basket at least 3 times during cooking to prevent sticking. Cook in batches if your air fryer is small.
While the chicken cooks, combine all the sauce ingredients in a microwave-safe bowl and stir together. Microwave on high for 3 minutes, stirring every minute, until the sauce is hot and slightly thickened.
Transfer the cooked chicken from the air fryer to a bowl or pan and toss with the warm sauce to coat thoroughly.
Sprinkle sesame seeds and chopped spring onions over the chicken and serve immediately with boiled or egg fried rice.