In a medium saucepan, whisk together orange juice, sugar, vinegar, ginger, garlic powder, and red pepper flakes, if using, over medium heat. Simmer 3 minutes, or until sugar is dissolved.
In a small bowl, whisk together cornstarch and water to form a paste. Whisk into the sauce and simmer 5 minutes more, or until thickened. Remove from heat and stir in the orange zest.
Preheat the oven to 325°F. Line a rimmed baking sheet with foil.
In a large zip-top bag, shake the chicken, cornstarch, garlic salt, salt, and pepper until the chicken is evenly coated. In a shallow bowl, add the egg.
In a large frying pan, heat ¼ cup oil over medium heat. Using a fork, dip ½ of the chicken pieces in egg and place in the frying pan. Fry each side 2 minutes, or until golden. Transfer to baking sheet. Dispose of the burnt oil and heat the remaining ¼ cup oil. Repeat process with the remaining chicken.
Pour the sauce over the chicken and stir to coat. Bake 20 minutes. Flip the chicken to evenly coat in sauce. Bake an additional 15 to 20 minutes.
Sprinkle with green onions and serve with steamed rice and vegetables. Enjoy!
