In a bowl, soak chicken pieces in buttermilk for 15–20 minutes.
In another bowl, combine cornstarch, garlic powder, salt, and pepper.
Heat vegetable oil in a deep skillet or pot to 350°F (175°C).
Remove chicken from buttermilk, shake off excess, then coat evenly in cornstarch mixture.
Fry chicken in batches for 4–5 minutes, or until golden and crispy.
Transfer to a paper towel-lined plate to drain excess oil.
In a small bowl, whisk together mayonnaise, sweet chili sauce, sriracha, honey, and rice vinegar until smooth.
Place fried chicken in a large bowl, drizzle with bang bang sauce, and toss gently to coat.
Garnish with chopped green onions and sesame seeds. Serve hot!
