Place chicken pieces in a large resealable bag and set aside.

In a medium saucepan, combine chicken broth, orange zest, orange juice, vinegar, soy sauce, sugar, ginger, onion, garlic, Sriracha, and pepper. Whisk well.

Measure out 2/3 cup of the mixture and pour it over the chicken in the bag. Seal the bag, pressing out excess air, and press chicken into the marinade.

Place the bag in a bowl or baking dish and refrigerate for 30 minutes.

Meanwhile, heat the remaining sauce mixture over medium heat until it just starts to boil, stirring frequently.

In a small bowl, whisk together cornstarch and water. Stir this mixture into the sauce.

Reduce heat to medium-low and cook the sauce for 1-2 minutes, stirring constantly, until thickened. Then, remove from heat.

Pour vegetable oil into a large cast iron Dutch oven, filling it about 1 1/2 - 2 inches deep, and heat the oil to 350 degrees Fahrenheit.

In a shallow dish, whisk eggs until well blended. In another shallow dish, pour the remaining 1 1/4 cups of cornstarch.

Remove the chicken from the refrigerator and drain off the marinade. Dip each chicken piece into the egg, then coat evenly with cornstarch.

Carefully place about one-third of the chicken pieces into the preheated oil and cook for 5-7 minutes until golden, turning once during cooking. Use a skimmer to remove the fried chicken from the oil and transfer it to a paper towel-lined cookie sheet to drain excess oil.

Repeat the process with the remaining chicken, working in two more batches. Then, pour the drained fried chicken into a bowl and toss it with the sauce.

Serve the orange chicken warm over white or brown rice, garnished with green onions and sesame seeds if desired.