Whisk together the cornstarch and egg whites with a fork in a bowl until almost frothy, about 1 minute. Add the chicken pieces to the mixture and allow to sit for 5 to 10 minutes.
Heat about 2 inches of vegetable oil in a heavy-bottomed pot until a deep-fry thermometer inserted in the oil registers 350°F/175°C.
Working in batches, carefully drop pieces of chicken (one by one to keep them from sticking together) into the oil and move it around, 2-3 minutes or until light golden.
Let the pieces drain on a plate lined with paper towels for 2 to 3 minutes.
Once the chicken has cooled, place in a freezer ziploc bag.
Sauce
In a small bowl, whisk together the orange juice, soy sauce, sugar, vinegar, sesame oil, salt, crushed red pepper, garlic and ginger (and orange zest, if using) and cornstarch. To freeze, transfer to a sandwich size ziploc bag.
To Freeze
Place cooked chicken in Ziploc freezer bag along with sauce packet and freeze.
To Prepare
Thaw sauce. Heat a nonstick skillet and whisk together sauce plus 1/4 cup water. Heat until bubbling and starting to thicken, about 3-4 minutes.
Heat chicken in the oven at 350°F/175°C, until completely heated (usually 15-20 minutes).
Coat the chicken with Orange Sauce. Serve over rice. Garnish with green onions.