• Place steaks on a cutting board and using a meat tenderizer, pound to ¼ inch thick. Season both sides generously with salt and pepper.
• In a medium bowl, combine flour, baking powder, onion powder, garlic powder, salt and pepper. Mix until well combined.
• In another bowl, combine egg, buttermilk, and ¼ cup of seasoned flour.
• Pour oil into a deep cast iron skillet and heat until 325℉.
• While the oil is heating, dredge a steak into flour to coat, shaking off excess. Dip into the buttermilk batter, allowing excess to drip off. Press in flour again to coat both sides. Set aside on a wire rack and repeat with remaining steaks.
• Fry in batches, if necessary and fry 3 - 4 minutes. Flip and fry another 3 - 4 minutes or until it's golden brown. Set aside an repeat with remaining steaks.
• Assemble sandwiches. Add mayo to buns and top with lettuce and tomato.

If making the gravy:

• Drain the oil from the skillet, reserving ¼ cup oil. Return skillet to medium low heat and add the ¼ cup oil back. Whisk in remaining flour, scraping the bottom to get any solids off.
• Stir in the milk and bring gravy to a simmer. Cook, stirring often, for 5 - 7 minutes until thickened. Season with salt and pepper.