In a bowl, toss the chicken pieces with cornstarch until evenly coated.
Heat the vegetable oil in a wok or large skillet over medium-high heat. Fry the chicken pieces in batches until golden brown and crispy. Remove from the pan and set aside.
In the same pan, add a bit more oil if needed. Sauté the minced garlic, ginger, and dried red chilies until fragrant.
In a separate bowl, mix together the soy sauce, hoisin sauce, rice vinegar, sugar, and water. Pour the sauce mixture into the pan with the garlic, ginger, and chilies.
Bring the sauce to a simmer, then add the fried chicken back into the pan.
Stir to coat the chicken pieces evenly with the sauce.
If desired, stir in the cornstarch-water mixture to thicken the sauce.
Serve hot with steamed rice and your favorite vegetables. Enjoy your homemade General Tso's Chicken!