Place the chicken breast pieces into a shallow dish. Add the buttermilk and hot sauce, if using. Turn the chicken pieces a few times to coat.
Let chicken marinate for at least 30 minutes.
Make the seasoning (see below).
Heat oil to 350 F in a Dutch oven, skillet or deep fryer.
Working in batches if needed, remove chicken bites from the marinade. Shake off excess and transfer to the seasoning. Coat well on all sides.
Transfer to the hot oil and fry 5-6 minutes per side or until golden brown and cooked thoroughly. Remove to a wire rack or paper towel-lined plate to drain.
Serve with your favorite dipping sauces.
For the seasoning
In a shallow baking dish or large resealable bag or container, whisk together the all-purpose flour, cornstarch, smoked paprika, garlic powder, onion powder, and salt. Whisk together.
Add in a few tablespoons of the buttermilk from the chicken marinade and mix.