Cut chicken into bite-sized pieces
Season with salt and pepper
Coat chicken in cornstarch
Dip in beaten egg if desired
Fry chicken until golden and cooked through
Drain on paper towels
Mix sauce with soy sauce, rice vinegar, sugar, garlic, ginger, and chili paste
Heat oil in a pan
Sauté garlic and ginger briefly
Add sauce ingredients and simmer until thickened
Add fried chicken to the sauce
Toss until evenly coated
Serve hot with rice or steamed vegetables