In a medium sized bowl, combine the flour, cornstarch, garlic powder, onion powder, paprika, salt, and pepper. Whisk to combine. To the same bowl, add the buttermilk, sriracha sauce, and egg. Whisk until a smooth batter forms. If the batter is too thick, add 1 tablespoon of buttermilk at a time until a smooth consistency is achieved.
In a shallow dish, add the panko bread crumbs.
Toss the chicken pieces into the batter, making sure each piece is completely coated into the batter.
Coat the chicken pieces in the panko breadcrumbs a few at a time, adding more breadcrumbs if needed.
In a large skillet, or deep fryer, heat vegetable oil to about 350°F (175°C). Carefully add the breaded chicken in batches, making sure not to overcrowd the pan. Fry for about 5-6 minutes, or until golden brown and cooked through. Remove from the oil and drain on a paper towel-lined plate.
Drizzle or coat the crispy chicken in the prepared bang bang sauce and serve. Garnish with fresh parsley or green onions if desired. Enjoy