In a large saucepan combine 1 1/2 cups water, orange juice, rice vinegar, soy sauce, and sesame oil. Blend well over medium-high heat for a few minutes. Stir in brown sugar, orange zest, ginger, garlic and red pepper flakes. Bring to a boil.
Combine 3 tablespoons of cornstarch with 2 tablespoons of water and mix thoroughly. Slowly stir cornstarch mixture into sauce, simmer and stir until it thickens. Hold sauce on the stovetop over low heat.
Heat a dutch oven with vegetable oil to 355 degrees.
Combine cornstarch, salt, and pepper. Prepare a bowl with beaten eggs, another with panko bread crumbs and another with corn starch. Dip chicken pieces in egg mixture, dredge in cornstarch, then again in the eggs and finally in the panko breadcrumbs. Working in batches fry chicken until golden brown and completely cooked about 4 minutes.
Pour sauce over breaded chicken, toss, and garnish with green onions.