In a mixing dish, whisk together all of the sauce ingredients and put aside. In a small dish, mix together the egg, salt, pepper, and 1 tablespoon of oil. Put 1/2 cup of cornstarch and flour into a shallow dish and whisk well to combine. Add enough oil to a big frying pan over medium-high heat to deep fry the chicken pieces. Preheat the oil to 375 degrees Fahrenheit. As soon as the oil is heated, dunk the chicken chunks in the beaten eggs first, then in the flour mix before placing them in the pan. Do not overfill the pan with chicken pieces; if necessary, cook in groups. Fry the chunks for 3 to 4 minutes on each side, or until golden and crunchy. Place on a cooling rack once fried. Remove the majority of the oil from the pan, reserving about 1 tablespoon. Pour in the orange sauce and bring it to a boil. Take the pan off the heat and mix in the cooked chicken until thoroughly covered. Serve with rice with a garnish of orange zest, sesame seeds, and green onions, if preferred.