In a medium bowl, combine chicken, salt, and egg, and mix well. Cover and set aside for 15 minutes.
When the chicken is done marinating, add cornstarch to the mixture.
In a heavy-bottomed skillet, heat vegetable oil over medium high heat. Add chicken all at once, spread out into an even layer, and cook until golden brown on both sides, turning once. Transfer to a paper towel lined plate, reserving about 1 tablespoon of oil in the skillet.
Add garlic, ginger, onions, pepper, and cook for 2 minutes.
In a medium bowl, whisk together orange juice, soy sauce, rice vinegar, sugar, cornstarch, and orange zest. Stir in the sauce mixture, stirring continuously, until the sauce has thickened.
Return the cooked chicken to the skillet and toss to coat well. Serve immediately.