Preheat oven to 425º F. Spray a large sheet pan with cooking spray and set aside.
Using 2 pie plates, add the beaten eggs to one and mix the panko and flour in the other. Dredge each chicken piece in the egg and then in the panko-flour mixture and add to the prepared baking sheet. Repeat with remaining chicken. Spray with cooking spray and bake for 10 minutes. Turn the pieces, then continue to cook for another 10 minutes, or until chicken is no longer pink the center, or to your liking.
Meanwhile, add the orange juice, orange zest, soy sauce, brown sugar, mirin, rice vinegar, sriracha, garlic and ginger to a medium saucepan. Bring to a low boil over medium heat, stir occasionally, turn heat down to low to simmer. When the chicken is just about done, add the corn starch to the orange juice mixture and bring to a boil. Heat until thickened enough to coat a spoon. Remove from the heat.
In a large serving bowl add the cooked chicken and top with the orange chicken sauce, toss lightly to coat. Sprinkle with sesame seeds and green onions and serve with steamed white rice.