Cube the chicken into 2-inch cubes. Don't cut them too small, as this will cause them to dry out in the air fryer.
Add cubed chicken to a large mixing bowl. Top with cornstarch, garlic powder, onion powder, salt, and pepper. Mix together to fully coat all sides of the chicken.
Spray the air fryer basket or tray with nonstick spray. Add chicken in a single layer. Spray the tops of the chicken with more nonstick spray.
Air fry at 400 degrees F for 12 to 15 minutes, or until the outside of the chicken is golden brown and the inside reaches an internal temperature of 165 degrees F. Repeat until all of the chicken is cooked.
Meanwhile, in a medium-sized mixing bowl, combine all the sauce ingredients, besides the olive oil, garlic, ginger, and red pepper flakes. Whisk thoroughly until it is smooth and there are no clumps of cornstarch remaining. Set aside.
Heat olive oil in a large skillet over low heat. Add the garlic, ginger, and red pepper flakes. Cook for 30 seconds, stirring constantly so the garlic and ginger do not burn.
Pour in the sauce, increase the heat to medium, and simmer for about 8 to 10 minutes, or until the sauce thickens enough to coat the back of a spoon.
Add the chicken to the skillet and fully coat it in the thickened sauce.
Garnish with sesame seeds and sliced green onions. Serve with a side of white or brown rice.