Begin by flattening the chicken breasts. Using a sharp knife, cut 3-4 vertical slits about ½ way deep in each chicken breast, going vertically along the longest side of the breast. Cut on the underside, leaving the top side smooth.
Place each chicken breast between two pieces of wax or parchment paper. Place parchment paper on a wooden cutting board.
Using a mallet, rolling pin or wine bottle, hit the chicken breast repeatedly to flatten out the meat. Flatten to about ½ an inch thick all over. The chicken will plump back up when cooked.
In two bowls, prepare your dredge. In one bowl, put your buttermilk (or pseudo buttermilk- see note below). In the other, combine flour and rub. You want the flour mixture to be well-studded with seasoning.
Preheat your grill to 450° and place a deep-sided cast iron pan on the grill. Get it very hot.
Pour in vegetable oil and allow to heat until the oil reaches 350°.
Dredge your chicken!
Dip each flattened chicken breast first in the seasoned flour mixture.
Shake off excess, and dunk fully in buttermilk.
Shake off excess and return to flour mixture, coating well.
Gently shake off excess, but leave lots of breading on the chicken and especially in the nooks and crannies.
Transfer dredged chicken breasts to a wire rack. Repeat with each remaining breast.
When oil is hot, cook chicken breasts, one at a time.
Cook for about 5 minutes per side, until well browned. Flip and continue cooking.
Chicken should reach 165° internal temperature.
Remove from oil, return to a pan with a wire rack, and place in a warm oven to hold.
Repeat frying steps for each chicken breast.
When you're cooking your last breast, put buffalo sauce in a small saucepan and begin to heat through.
Toast your buns to your liking.
Transfer heated sauce to a bowl large enough to accommodate the fried chicken.
Using tongs, dunk fried chicken breast in heated sauce, coating well.
Place on prepared, toasted buns. Top with pickle slices and top bun.
You may need a fork and knife for this sandwich!