This seasoning mixture closely resembles Wing Stop's Louisiana Dry Rub flavor. They are mouth-watering. You can use wings too, but decrease the frying time by 2 minutes so the wings do not dry out. I suggest making plenty of the spice rub, you will want to use it on MANY things you cook.
Place chicken pieces and buttermilk (or milk and vinegar) in a large zipper bag (or covered container.) Marinate at least 1 hour or overnight in the refrigerator. Turn bag periodically to be sure chicken marinates evenly.
Drain chicken, discard milk. Pat chicken THOROUGHLY dry with paper towels. If chicken is not well-dried when it is placed in the hot oil, the oil could sputter and splash, causing serious burns.
Place the flour in a zippered food storage bag and toss each dried piece of chicken to coat. Place flour coated chicken pieces on a tray in the fridge for at least 10 minutes while oil heats.
In a deep kettle, or commercial deep fryer, heat oil to 325 degrees farenheit, 185 degrees celcius. Check temperature with a safe, candy or deep-fryer thermometer that is designed to measure at high temperatures.
When oil is ready, add chicken to hot oil with tongs or a long handled spoon to avoid burns. Do not over crowd the pan, fry in several batches. Fry pieces 8 to 10 minutes ( about 5 minutes per side, thicker pieces may need additonal time in the oven to finish cooking) until golden brown. Remove from oil and drain on paper towels or a cooking rack for about 1 minute.
Place drained chicken pieces into the bowl with the spice mixture and using tongs or long handled spoons, toss chicken to coat in the seasoning (make more seasoning if needed.) Transfer to a baking sheet and hold pieces in a warm (200 degree) oven until all pieces are cooked.
In a small sauce pan, combine ketchup with diced jalapeno and brown sugar. Heat thoroughly. Serve as a dipping sauce with chicken.