Coat the chicken in egg wash. Mix together 2 beaten eggs, about 1 tablespoon of the soy sauce, garlic powder, salt, and pepper until well combined. Add the chicken to the egg wash, ensuring that all pieces are coated. Allow to sit for 15-20 minutes.
While the chicken is in the egg wash mixture, prepare the sauce. In a medium bowl, mix together all sauce ingredients until well combined. Set aside.
In a large bowl, mix together flour and cornstarch. Add a few pieces of the chicken at a time to the flour mixture, tossing to coat evenly.
Preheat griddle to medium to medium-high heat (about 400-425℉).
Add enough oil to the heated griddle to shallow fry - about 4 to 5 tablespoons. Carefully place the floured chicken pieces in the heated oil, making sure that the pieces are not too close together so that they can crisp up and fry evenly. Cook on the first side for about 4-5 minutes, or until a nice golden color develops. Then flip to the second side and cook an additional 3-5 minutes, or until the internal temperature of the chicken is about 155-160℉. *NOTES - You can use a squirt bottle to apply extra oil near the chicken pieces as needed for them to shallow fry. Chicken is not done at 160℉, but it will continue to cook on the griddle with the sauce later.
Transfer the chicken to a wire rack or paper towels for the excess oil to drain off.
While the chicken is draining, cook the vegetables on the griddle until done to your liking. We prefer a tender-crisp so the veggies aren't too mushy. Then, add the cooked chicken back to the griddle with the veggies and mix together.
Pour on about half of the prepared sauce, mixing with the chicken and vegetables so that all pieces are coated. After the sauce reduces slightly, add the rest and mix together well.
When chicken is cooked through (165℉) and sauce is reduced to your liking, transfer the sesame chicken to a serving platter. *The sauce will continue to thicken as it cools, so be sure to not let it reduce too much on the griddle.
Sprinkle sesame seeds on the chicken. Serve sesame chicken hot over white rice or fried rice.