In a bowl, mix cornstarch, flour, salt, and black pepper.
Coat the chicken pieces in the dry mixture, shaking off excess.
Heat oil in a skillet over medium heat and fry the chicken pieces until golden and crispy. Remove and set aside.
In the same pan, add garlic and sliced red chili, sauté until fragrant.
Stir in sweet chili sauce, soy sauce, and sriracha. Simmer for 2 minutes.
Add the fried chicken back to the pan, tossing to coat evenly in the sauce.
Garnish with green onions and serve immediately.