In a large heavy bottom saucepan or high sided skillet, heat the 4 cups of vegetable oil to 375 degrees F (190 degrees C).

In a medium sized bowl, put beaten egg, salt, pepper, and sugar into the bowl and mix well. Add cubed chicken and toss to coat the chicken in the egg, then shake in the cornstarch a little at a time and stir in well, until the chicken is coated well in the corn starch and egg mixture.

In small batches, carefully drop the chicken pieces into the oil one by one, until the batter becomes a pale brownish color and the chicken floats, about 3 minutes. Remove the chicken onto a paper towel-lined plate and fry the next batch Repeat until all chicken is fried.

Once all the chicken is fried, refry the chicken until the pieces are a golden brown, about 2 minutes. Drain again on a fresh paper towel lined plate, then transfer into paper-towel lined large heat-safe bowl. Keep all chicken in that bowl after draining.

In a small saucepot, heat 2 tablespoon vegetable oil over medium heat and add green onion, ginger, garlic, red pepper, and orange zest. Stir for one minute, until garlic is fragrant. Add sugar, soy sauce, vinegar, orange juice, and broth and stir in well. Bring mixture to a boil, then turn down to medium high heat to cook for 5 minutes.

Dissolve the 1 tablespoon of cornstarch in ¼ cup water and stir into the sauce. Allow to cook and thicken for 2 minutes.

Remove paper towel from bowl and pour sauce over the chicken, stir well to coat the chicken.

Serve with rice and vegetables