Pat chicken pieces completely dry with paper towels. In a large bowl, whisk together flour, cornstarch, baking powder, salt, pepper, and garlic powder.

In a separate bowl, beat eggs with cold water until well combined. Set up your breading station with flour mixture, egg wash, and flour mixture in three separate bowls.

Dip each chicken piece into flour mixture, then egg wash, then back into flour mixture, pressing firmly to create thick, clumpy coating. Place on a wire rack.

Heat vegetable oil in a deep skillet to 350°F. Fry chicken in batches for 5-6 minutes until deep golden brown and internal temperature reaches 165°F. Drain on wire rack.

For the sauce, combine orange juice, orange zest, sugar, soy sauce, rice vinegar, garlic, and ginger in a saucepan. Bring to simmer over medium heat.

Stir in cornstarch slurry and cook for 2-3 minutes until thickened and glossy. Toss fried chicken in sauce immediately and garnish with sesame seeds and green onions.