Place the chicken pieces in a pan or shallow bowl, pour the buttermilk over, and let marinate for 1 hour at room temperature. Pour off the buttermilk add reserve 1 cup. Sprinkle 2 tablespoons of the seasoning mix all over the chicken pieces and pat it in well with your hands. Combine the flour 2 ½ teaspoons of the seasoning mix in a shallow bowl. Heat the oil in a large non stick fry pan over high heat until very hot. Toss the chicken in the seasoned flour, shaking off the excess, and add to the oil, skin side down, in a single layer. Cover the pan and reduce the heat to medium, and fry, checking occasionally to make sure the chicken is not burning, until browned on one side, about 5 to 6 minutes. Turn the chicken pieces over, cover, and fry, checking occasionally, until a rich, golden brown. Remove from the pan and drain on paper towels.