Marinate Chicken: Place the chicken pieces in a bowl and pour buttermilk over them. Let it marinate for at least 30 minutes to tenderize the chicken.
Prepare Breading: In a shallow dish, combine flour, paprika, garlic powder, onion powder, salt, and black pepper. In another dish, place panko breadcrumbs.
Coat Chicken: Remove chicken from the buttermilk, allowing excess to drip off, then dredge in the flour mixture, followed by the panko breadcrumbs, ensuring an even coating.
Fry Chicken: Heat oil in a deep skillet or pot over medium-high heat. Once hot, fry the coated chicken pieces in batches until they are golden brown and cooked through, about 4-5 minutes per side. Drain on paper towels.
Make the Sauce: In a bowl, mix mayonnaise, sweet chili sauce, and sriracha until well combined. Adjust the heat to your preference.
Combine: Toss the crispy chicken in the sauce until well coated. Serve hot, garnished with chopped green onions.