1. Cut chicken pieces into 2-inch squares and place in large bowl. Stir in egg, salt, pepper and 1 tablespoon oil and mix well.
2. Stir cornstarch and flour together in separate dish. Add chicken pieces, stirring to coat.
3. Heat oil for deep-frying in wok or deep-fryer to 375 degrees.
4. Add chicken pieces, small batch at time, and fry 3 to 4 minutes or until golden and crisp. (Do not overcook or chicken will be tough.) Remove chicken from oil with slotted spoon and drain on paper towels. Set aside.
5. Mix soy sauce, water, sugar, and vinegar in separate bowl.
6. Clean wok and heat 15 seconds over high heat. Add 1 tablespoon oil. Add ginger and garlic and stir-fry until fragrant. Add and stir-fry crushed chilies and green onions. Add rice wine and stir 3 seconds.
7. Add sauce mixture to wok and bring to boil.
8. Add cooked chicken, stirring until well mixed.
9. Stir water into remaining 1 tablespoon cornstarch until smooth. Heat until sauce is thickened.
10. Stir in 1 tablespoon sesame oil and grated orange zest to the sauce for flavor. Serve immediately, while hot