Cut boneless chicken into bite-sized pieces
Season with salt and pepper
Dredge chicken in cornstarch or flour
Dip chicken in beaten egg
Coat again with cornstarch or flour
Heat oil in a pan or wok over medium-high heat
Fry chicken until golden and cooked through
Remove chicken and drain on paper towels
In a saucepan, combine orange juice, soy sauce, sugar, rice vinegar, garlic, ginger, and orange zest
Bring the sauce to a simmer
Mix cornstarch with water to make a slurry
Stir the slurry into the sauce
Cook until the sauce thickens
Add fried chicken to the sauce
Toss until evenly coated
Serve hot with rice or vegetables