In a medium-sized bowl, combine the sweet chili sauce, soy sauce, rice vinegar, sesame oil, minced garlic, grated ginger, black pepper, and red pepper flakes if you enjoy some heat. Stir until all ingredients are well mixed and fragrant.
Cut the chicken into bite-sized pieces to ensure even cooking and better absorption of flavors from the marinade.
Add the chicken pieces to the marinade ensuring they are well coated on all sides. Cover with plastic wrap or transfer everything into a resealable plastic bag and marinate in the refrigerator for at least 30 minutes.
Preheat your air fryer to 380°F (193°C) while you finish preparing your chicken.
Lightly spray the air fryer basket with cooking spray or use a parchment paper liner to prevent sticking during cooking. In a small bowl, add cornstarch which will help create that crispy exterior when air frying.
Remove the chicken pieces from the marinade allowing excess liquid to drip off before tossing them gently in cornstarch until evenly coated. Place in a single layer in your air fryer basket and cook at 380°F (193°C) for about 12-15 minutes while shaking halfway through for even crispiness.