Combine the cubed chicken with Salt (To taste), Black Pepper (To taste), egg, cornstarch, and just enough water until the batter is thick like maple syrup; mix well to coat evenly.
Heat neutral oil to 300°F (150°C), add the coated chicken pieces and fry for about 5 minutes or until golden brown, adjusting heat as needed to maintain oil temperature; remove and drain excess oil.
In a pan, heat a little oil and stir-fry garlic and scallion whites until fragrant, then add soy sauce, oyster sauce, orange juice, cooking wine, white vinegar, and sugar.
Slowly add the cornstarch slurry (cornstarch mixed with water) while stirring until the sauce thickens to a glossy consistency.
Add the fried chicken to the sauce and toss for about 30 seconds until evenly coated.
Garnish with sliced scallions and orange zest.
