**Marinate the Chicken**
- In a bowl, combine buttermilk, garlic powder, paprika, salt, and black pepper. Add chicken pieces and mix to coat. Let marinate for at least 30 minutes or up to 4 hours in the refrigerator.
**Prepare the Coating**
- In another bowl, mix flour and cornstarch.
**Coat the Chicken**
- Remove chicken from the marinade, allowing excess buttermilk to drip off. Coat each piece in the flour mixture, pressing gently to adhere.
**Fry the Chicken**
- Heat oil in a skillet or fryer to 350°F (175°C). Fry chicken pieces in small batches until golden brown and crispy, about 4–5 minutes per batch. Drain on a paper towel-lined baking sheet.
**Make the Bang Bang Sauce**
- In a bowl, whisk together mayonnaise, sweet chili sauce, sriracha, and honey until smooth.
**Assemble and Serve**
- Drizzle the bang bang sauce over the fried chicken or serve it on the side as a dipping sauce. Garnish with chopped green onions or sesame seeds if desired.