In a large bowl, combine flour, cornstarch, salt, pepper, garlic powder, onion powder, and paprika. In another bowl, beat the eggs. Dip each piece of chicken into the egg, then coat thoroughly in the flour mixture. Set aside on a plate.

Heat the vegetable oil in a large skillet or deep fryer over medium-high heat. Once hot, carefully add the coated chicken pieces in batches, making sure not to overcrowd the pan. Fry until golden brown and crispy, about 5-7 minutes per batch. Remove and drain on paper towels.

In a saucepan over medium heat, combine orange juice, sugar, soy sauce, rice vinegar, and orange zest. Stir until the sugar dissolves. Bring to a simmer.

Add the cornstarch mixture to the saucepan, stirring constantly until the sauce thickens, about 2-3 minutes. If desired, add red pepper flakes for some heat.

Toss the fried chicken pieces in the orange sauce until well coated. Serve immediately.