In a large bowl, whisk together the ingredients for the chicken coating until light and frothy. Toss in the chicken pieces and let sit at room temperature. Set up a cooling rack over a baking sheet lined with paper towels and heat up 1-2 inches of oil in a high-sided, heavy bottomed pot over medium high heat until oil reaches 350°F. Preheat your oven to its lowest setting.

While the oil is heating up, place 1 cup of cornstarch in a bowl. Spoon out 2 tablespoons of the chicken coating and whisk into the cornstarch to form small clumps. These will add extra crispy bits to your chicken. Working in batches: throughly coat several pieces of chicken in the cornstarch, shake off the excess, then gently add the chicken to the hot oil. Deep fry each batch until golden brown and crispy (about 5-6 minutes) flipping as needed. Drain the chicken on your prepared rack and keep warm in the oven.

Once all of your chicken is done and resting in the oven, make the sauce: whisk together 1 tablespoon of Shaoxing wine with 1 tablespoon of cornstarch until smooth, then whisk in the chicken stock, soy sauce, sugar, vinegar, and toasted sesame oil. In a large skillet, heat up a bit of oil over medium heat and stir fry the garlic, ginger, and chili (if using) until soft but not brown, 2-3 minutes. Add the sauce ingredients and cook, stirring, until the sauce comes to a boil and starts to thicken.

Remove from heat, then add the chicken and toss. Toss throughly to coat and enjoy immediately.