In a mixing bowl, combine flour, cornstarch, salt, and pepper. Dip chicken pieces into the beaten eggs, then coat with the flour mixture.

Heat oil in a deep fryer or large pot to 350°F (175°C). Fry the chicken in batches until golden brown and cooked through, about 5-7 minutes. Remove and drain on paper towels.

In a saucepan over medium heat, combine orange juice, sugar, soy sauce, rice vinegar, ginger, garlic, and red pepper flakes. Bring to a simmer.

Once simmering, add the cornstarch mixture and stir until the sauce thickens, about 2-3 minutes. Remove from heat.

In a large skillet, combine the fried chicken with the orange sauce. Toss to coat evenly.

Serve hot, garnished with sliced green onions and sesame seeds.