Preheat oven to 350 degrees. Spray a 9 by 12-inch baking pan with cooking spray.
Whisk together the sugar, hot sauce, vinegar, and red pepper flakes.
Cut the chicken into 1-inch pieces. Sprinkle with salt and pepper and toss to coat. Put the corn starch in a large bowl, add the chicken, and toss to coat. Heat the oil in a large skillet over medium-high heat. Put the eggs in another bowl.
Heat the oil in a large skillet over medium-high heat until hot. Working next to the stove, dip a few of the chicken pieces into the eggs, shake off the excess and put into the skillet in an even layer. Working in batches, cook the chicken for 3-4 minutes or until lightly browned. Place in the prepared baking dish. When done with all the chicken, add the sauce to the pan, toss to coat and bake for 30 minutes, stirring halfway through.