Cut chicken breasts into bite sized pieces. In a medium-sized mixing bowl, whisk together egg whites, cornstarch, salt and white pepper. Submerge chicken breast pieces in mixture and set aside.
In a small saucepan, stir together orange juice, orange zest, rice vinegar, soy sauce, brown sugar, ginger, and red pepper flakes. Bring to a simmer.
In a small bowl, whisk together water and cornstarch. Pour slurry into sauce mixture and stir in until thickened. Remove from heat and set aside.
Meanwhile, pour 2 inches of vegetable oil into a large, heavy bottom pot. Heat to 350 degrees. Working in small batches, fry chicken pieces until cooked through and golden brown, about 3 to 4 minutes. Remove from oil and drain on a paper towel lined plate.
Toss fried chicken pieces together with sauce. Serve immediately and garnish with green onions for color.