01 - In a large mixing bowl, thoroughly toss chicken pieces with cornstarch, salt, and black pepper until evenly coated.
02 - Heat vegetable oil in a large skillet or wok over medium-high heat. Add coated chicken pieces in a single layer and cook for 5 to 6 minutes, turning as needed, until golden brown and cooked through. Transfer chicken to a plate and set aside.
03 - In a separate mixing bowl, whisk together soy sauce, honey, brown sugar, rice vinegar, sesame oil, grated ginger, minced garlic, and chili flakes (if using) until smooth.
04 - Pour the sauce mixture into the same skillet. Bring to a simmer over medium heat, and stir continuously for 2 to 3 minutes until the sauce begins to thicken.
05 - Return cooked chicken to the skillet. Toss thoroughly to coat every piece in the sauce, and continue to cook for 2 to 3 minutes until sauce becomes glossy and sticky.
06 - Remove skillet from heat. Sprinkle with toasted sesame seeds and sliced spring onions before serving.