Bake the popcorn chicken according to package instructions until golden and crispy. While the chicken cooks, I like to prep all the sauce ingredients so I can move quickly once I start cooking.
In a bowl, whisk together chicken stock, brown sugar, soy sauce, hoisin sauce, rice wine vinegar, cornstarch, and sesame oil. The mixture should look smooth and slightly glossy. This will become the sticky glaze.
Heat vegetable oil in a skillet over medium heat. Add garlic, ginger, and chili paste. Stir for about 30 seconds until fragrant—this step really builds the base flavor.
Pour in the whisked sauce mixture and stir well. Let it simmer for 1–2 minutes until it thickens slightly. Don’t walk away, as cornstarch thickens quickly.
Once the sauce looks shiny and thick, toss in the baked popcorn chicken. Stir gently so each piece is coated in the sticky glaze. The chicken should look glossy and flavorful.
Transfer to a serving dish, sprinkle with scallions and sesame seeds, and serve hot. It’s best enjoyed right away when the chicken is still crisp.