In a small saucepan over medium heat whisk together the sesame oil, ginger, garlic, red pepper flakes, orange zest, soy sauce, water, sugar, white vinegar, rice wine vinegar and the white part of the green onions.
Simmer, stirring occasionally, until the sauce has reduced by about half. Once the mixture is reduced, make a slurry by whisking together the cornstarch with 2 tablespoons of cold water.
Whisk the slurry into the sauce and continue to simmer until the sauce is thick and coats the back of a spoon. Remove from heat then strain the sauce through a fine mesh strainer and set aside.
For the chicken:
Cut the chicken into 1-inch cubes and place in a medium bowl. Toss with the orange juice, cover and marinate for at least an hour and up to overnight.
Fill a large cast iron skillet with at least 1-inch of the oil and heat to 350ºF (180ºC).
In a medium shallow bowl whisk the eggs. In another medium shallow bowl whisk together the flour, cornstarch, salt and pepper.
Working in batches dredge the chicken in the egg and then in the flour, shaking off any excess flour.
Fry the chicken in batches, until golden brown on both sides, about 4 minutes each side. Remove to a paper towel lined plate to drain and repeat the process with remaining chicken.
Add the chicken to a medium mixing bowl and toss with the sauce.
Serve topped with the remaining green onions with a side of rice.