Preheat the air fryer at 400°F/200°C for 5 minutes.
Dice or cube the chicken if desired. Add the chicken to a Ziploc bag along with cornstarch, salt, and pepper. Shake well to coat evenly.
Spray the bottom of the air fryer basket with avocado or olive oil.
Remove the chicken from the bag and shake off any excess coating.
Add the chicken in a single layer in the air fryer basket and spray the tops with avocado oil or olive oil.
Cook the chicken in the air fryer at 400°F/200°C for 4-8 minutes, or until it is almost cooked and slightly browned. Flip at the halfway point.
Whisk sauce ingredients together in a cake barrel dish or other oven safe dish. Add in the chicken and cook for an additional 3-5 minutes, or until the chicken and sauce is warmed through. Chicken will register at 165˚F/74˚C with an instant read thermometer once it is finished cooking. Add time as necceassry until the chicken is cooked through.
Optional. With remaining sweet and sour sauce, make a thicker blend. Combine 1 tablespoon of cold water with 1 tablespoon of cornstarch together in a bowl. Combine with warm to simmering sauce until thickened.