For the chicken:In a small bowl, whisk the egg with salt and pepper. Dip the chicken pieces into the mixture.In another bowl, mix the cornstarch and all-purpose flour. Then piece by piece, dunk the wet chicken into the flour mixture, tossing to coat. Repeat for all of the chicken.
Heat the oil in a frying pan, then add the chicken in a single layer in the pan.Fry the chicken pieces until golden brown, stirring occasionally medium heat. Then transfer to a paper towel lined plate and set aside.
For the sauce:Add sesame oil to the pan and sauté the garlic, ginger and chili flakes for a minute, stirring occasionally.Add soy sauce, white wine, orange juice, brown sugar and orange zest into the pan; sauté for 1 minute.
Mix water with cornstarch in a small bowl, making sure there are no clumps. Pour into the pan, and stir into the sauce. Heat over medium until the sauce thickens.Add the chicken back to the pan and toss until evenly coated in sauce. Garnish with green onions and sesame seeds and serve immediately.