Cut the chicken into bite-sized pieces and coat with cornstarch.
Deep-fry the chicken until golden brown and crispy.
Heat a wok or pan with a little oil and sauté garlic and ginger until fragrant.
Add soy sauce, rice vinegar, brown sugar, ketchup, chili flakes, and a little water to prepare the sauce.
Simmer the sauce until it slightly thickens.
Add the fried chicken and toss well until evenly coated with the sauce.
Garnish with green onions and sesame seeds. Serve hot with steamed rice.