01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
02 - Season chicken pieces with salt and pepper, then toss with cornstarch to coat evenly.
03 - Arrange coated chicken in a single layer on the prepared baking sheet. Bake for 20 minutes, flipping halfway through, until golden and cooked through.
04 - While the chicken bakes, combine orange juice, orange zest, soy sauce, rice vinegar, honey (or brown sugar), garlic, ginger, sesame oil, and chili flakes in a saucepan. Bring to a simmer over medium heat and cook for 5–7 minutes, stirring frequently, until slightly thickened.
05 - Transfer baked chicken to a large bowl. Pour the orange sauce over and toss to coat thoroughly.
06 - Return the sauced chicken to the oven for an additional 5–7 minutes until caramelized.
07 - Garnish with sliced green onions, sesame seeds, and orange slices if desired. Serve immediately with steamed rice or vegetables.