In a small bowl, whisk together the chicken stock, soy sauce, rice vinegar, hoisin, chili-garlic sauce, brown sugar, ginger, and 1 tablespoon of the cornstarch. Set aside.

In a medium bowl, whisk together the eggs and 1 teaspoon of the salt. Add the chicken pieces and toss to coat. Set aside.

Whisk together the flour, the remaining ½ cup cornstarch, and the remaining ½ teaspoon salt in a large, shallow dish. Pour the oil to a depth of 1 ½ inches in a large skillet with high sides (you may have some leftover oil if using a slightly smaller skillet). Heat over medium-high until a deep fry oil or instant-read thermometer registers 350°F, about 5 minutes.

Once the oil has preheated, transfer the chicken pieces from the egg mixture to the flour mixture and toss to fully coat. Working in 2 batches, remove the chicken from the flour mixture and carefully place in an even layer in the hot oil. Fry, turning occasionally, until lightly golden brown, crispy, and cooked through, 5 to 6 minutes. Remove the chicken with a spider or slotted spoon to a plate lined with paper towels. Repeat with the remaining chicken pieces, adjusting the heat of the oil as needed to maintain 350°F.

Once all the chicken has cooked, carefully pour the hot oil into a metal saucepan to cool. Reserve the used oil for another use. Do not wipe the skillet clean. Return the skillet to medium-high heat. Add the soy mixture to the skillet and cook, stirring constantly, until thickened and slightly reduced, about 2 minutes. Add the fried chicken pieces and toss to fully coat, about 1 minute. Transfer the chicken to a serving platter and garnish with scallions and sesame seeds, if desired. This is best served immediately. Refrigerate leftovers in an airtight container for up to 1 day. Reheat in a pan over medium heat with a splash of water, or reheat individual servings in the microwave in 30-second bursts until heated through. Love the recipe? Leave us stars and a comment below!