Preheat oven to 325°F. Lightly grease a 9x13-inch baking dish.
Place cornstarch in a large zip-top bag. Add chicken and shake to coat.
In a shallow bowl, beat the eggs. Dip each cornstarch-coated chicken piece into the egg.
Heat oil in a large skillet over medium-high heat. Sear chicken pieces until golden but not cooked through.
Place seared chicken in the prepared baking dish.
In a medium bowl, whisk together all sauce ingredients.
Pour sauce evenly over the chicken.
Bake uncovered for 1 hour, turning the chicken every 15 minutes to coat well with the sauce.