Rub the chicken with garlic salt on all sides. Allow to rest for 30 minutes to 1 hour in refrigerator.
Beat the eggs well in a shallow dish; place the cornstarch in another shallow dish. Dip each piece of chicken into beaten egg and roll in cornstarch until thoroughly coated. Shake off excess cornstarch.
Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C). Cook the chicken, a few pieces at a time, until the crust is golden brown, about 5 minutes; drain on paper towels.
Preheat oven to 350 degrees F (175 degrees C). Line a 9x13-inch baking dish with aluminum foil. Place the chicken into the baking dish so the pieces touch each other.
Stir together the sugar, vinegar, water, ketchup, soy sauce, and hot pepper sauce in a saucepan over medium heat until the mixture comes to a boil and the sugar has dissolved. Pour the sauce over the chicken, coating thoroughly with sauce.
Bake the chicken in the sauce until the juices run clear, basting with sauce every 10 minutes, for 40 to 50 minutes. Turn the pieces about halfway through baking. An instant-read thermometer inserted near the bone should read 165 degrees F (74 degrees C).