Directions
In a bowl, combine the orange juice, orange zest, soy sauce, brown sugar, rice vinegar, garlic, ginger, and red pepper flakes. In a separate small bowl, stir together 1 tablespoon of cornstarch and the water. Set both mixtures aside. Season the chicken with the salt and black pepper. Toss the chicken with the remaining cornstarch until evenly coated. Heat the vegetable oil in a large skillet over medium-high heat. Cook the chicken in batches for 5 to 7 minutes until browned and fully cooked, then transfer it to a plate. Pour the orange mixture into the skillet and bring it to a simmer. Stir in the cornstarch and water mixture and cook for 1 to 2 minutes until thickened. Return the chicken to the skillet and toss until coated. Sprinkle with green onions and sesame seeds.