Combine brining ingredients in a mixing bowl, add cut steaks and marinate for 2 hours. Remove from brine. Pour buttermilk into the other mixing bowl and transfer brined steaks into the buttermilk for 30 minutes just before placing in the flour mixture.
Reserve 1 cup all-purpose flour for gravy roux. Put remaining flours, salt, and pepper into bag, close top, and mix by shaking. Remove steaks from buttermilk, place in seasoned flour mixture, and shake well to coat. Place on wire rack to let excess flour drop. Let coated steaks rest for 10 minutes before frying. Heat frying fat to 365 degrees. Place coated steaks in hot oil and cook 5-7 minutes. Turn each steak and fry 5-7 additional minutes. Total cook time should be 12 minutes. Steaks will be crispy, mahogany in color, and medium rare to medium. Place on a wire rack with paper towels underneath to catch any drippings.
To make brown gravy, spoon out 1 cup of the frying oil while the steaks are cooking and transfer the oil into a small saucepot for the gravy roux. Add 1 cup flour to frying oil and make a roux by whisking over low heat for 5 minutes, then whisk in chicken broth to make the gravy. Season with salt and pepper. To serve, spoon gravy over steaks.