Preheat oven to 325°F.

Cut chicken breasts into 1-inch pieces and season lightly with salt and pepper.

Place cornstarch in a large zip-top bag. Add chicken and shake to coat evenly.

Whisk eggs in a shallow bowl.

Heat oil in a large skillet over medium heat until hot and shimmering.

Dip cornstarch-coated chicken pieces into the beaten eggs and carefully place in the hot skillet.

Cook for 20–30 seconds per side until lightly golden (chicken will not be fully cooked).

Transfer chicken to a greased 9x13-inch baking dish in a single layer.

In a bowl, whisk together sugar, ketchup, apple cider vinegar, soy sauce, and garlic salt.

Pour sauce evenly over chicken.

Bake Baked Sweet and Sour Chicken for 1 hour, turning pieces once or twice during baking to coat evenly.

Serve hot over steamed rice.