Combine the salt, flour, black pepper, and cayenne in a large, shallow bowl. Dredge the chicken in the flour mixture, shaking off the excess. Set aside for about 15 minutes.
Pour the buttermilk into a second shallow bowl. Dip the chicken in the buttermilk, then again in the flour mixture.
In a heavy-bottomed Dutch oven (preferably cast iron), heat about 4 inches of vegetable oil over medium heat until the temperature registers 360° F on a deep-fry thermometer. Carefully place the chicken in the oil, using tongs. (Add the pieces slowly, so that the temperature does not drop, and work in batches to avoid overcrowding.) Fry the chicken until golden brown, turning once, 10 to 20 minutes, depending on the size of the pieces. Check for doneness by piercing the meat; the juices should run clear. Drain the chicken on paper towels set on a wire rack. If desired, the cooked chicken can be kept warm in an oven set on low.
Well, this was the first and last time I ever made fried chicken. The cayenne was unnoticeable. The thermometer didn't tell me the oil was too hot and the instruction that said 4 inches of oil was clearly a typo. So while we were fighting an oil fire, the chicken breading was turning a deep brown to black while the chicken was staying pink as you please. I ended up semi-blackening all the chicken for uniformity then baking it done in the oven for 35 minutes. I now have baking powder/soda not sure which in my lungs and besides, I dislike fried chicken.