In a medium saucepan, combine orange juice, sugar, vinegar, soy sauce, ginger, garlic, and red chili flakes. Heat over medium heat for about 3 minutes.
In a small bowl, mix 1 tablespoon of cornstarch with 2 tablespoons of water to form a slurry.
Slowly whisk the slurry into the sauce and continue cooking for another 5 minutes, or until the sauce thickens.
Remove from heat and stir in the orange zest. Set aside.
Prepare the Chicken:
In a shallow bowl, combine flour, cornstarch, and a pinch of salt.
In another shallow bowl, whisk the eggs.
Dip each piece of chicken into the egg mixture, then coat evenly in the flour mixture. Set aside.
Heat 2-3 inches of oil in a deep, heavy-bottomed pot over medium-high heat until it reaches 350°F (175°C).
Fry the chicken in small batches for 2-3 minutes, turning occasionally, until golden brown and crispy. Remove and drain on a paper towel-lined plate. Repeat with remaining chicken.
Assemble & Serve:
Toss the crispy chicken pieces in the orange sauce until evenly coate
Serve hot, garnished with chopped green onions and extra orange zest.
Enjoy with steamed rice or vegetables for a complete meal!