Preheat your oven to 400°F (200°C). This ensures that the chicken cooks evenly and gets that perfect golden-brown color.
In a mixing bowl, combine the chicken pieces with salt and pepper. Toss well to ensure that the chicken is evenly seasoned.
In a separate bowl, add the cornstarch. Dip each seasoned chicken piece into the beaten eggs, then coat it with cornstarch, shaking off any excess. This will create a nice crunchy texture once baked.
Line a baking sheet with parchment paper and drizzle it with 3 tablespoons of oil. Spread the coated chicken pieces in a single layer on the baking sheet. Bake in the preheated oven for 20-25 minutes, or until golden brown and cooked through, flipping halfway through for even cooking.
While the chicken is baking, prepare the orange sauce. In a saucepan over medium heat, combine the brown sugar, orange juice, rice vinegar, soy sauce, garlic, red chili flakes, and orange zest. Stir until the sugar is dissolved and the mixture is slightly thickened, about 5-7 minutes. In a small bowl, mix the additional teaspoon of cornstarch with a tablespoon of water to create a slurry. Add this to the sauce and stir until thickened.
Once the chicken is done baking, remove it from the oven and place it in a large mixing bowl. Pour the orange sauce over the chicken, tossing to coat each piece thoroughly.
Transfer the glazed chicken back to the baking sheet or serve it directly in a bowl. Garnish with chopped green onions for a fresh touch. Serve with steamed rice or your favorite side dish.