Combine orange juice, sugar, rice vinegar, soy sauce, garlic, chili flakes and ginger in a medium pan.
Cook over medium high heat for 3 minutes.
In a bowl combine 3 tablespoons cornstarch and 3 tablespoons water and mix together to make a slurry.
Add to the sauce and whisk to incorporate.
Cook until sauce thickens, about 5 minutes.
Remove from heat and set aside.
Combine remaining cornstarch and flour in a shallow dish and stir. Set aside.
Whisk eggs in small bowl.
Dip chicken pieces in egg wash and shake off excess liquid.
Dip in flour/cornstarch mixture and gently shake off excess.
Place on plate.
Heat several inches of oil in skillet over medium high heat to about 350.
Cook several pieces of chicken, turning frequently until golden brown (about 3 minutes).
Place chicken on a plate lined with paper towels. Repeat.
Add chicken back to pan over low heat.
Add orange sauce and toss chicken to coat. Heat for 8 minutes until warmed through.
Serve over rice and garnish with green onion, if desired.