Cut chicken into bite-sized pieces
Season chicken with salt and pepper
Coat chicken with cornstarch
Dip chicken in beaten egg
Coat chicken again with cornstarch
Heat oil in a pan or wok
Fry chicken until golden and cooked through
Remove chicken and drain excess oil
Mix soy sauce, rice vinegar, sugar, hoisin sauce, garlic, ginger, and chili flakes
Heat a little oil in a clean pan
Sauté garlic and ginger
Add the sauce mixture
Simmer until slightly thickened
Add fried chicken to the sauce
Toss until evenly coated
Garnish with green onions and sesame seeds
Serve hot with rice