Directions :

1. Preheat oven to 200 degrees. Line 1 rimmed baking sheet with parchment or foil. Line a second rimmed baking sheet with foil and set a wire rack on top.
2. In a large shallow bowl, whisk together flour, cayenne pepper, 5 teaspoons salt, and 1 teaspoon pepper.
3. In a second shallow bowl, whisk egg with baking powder and baking soda. Whisk in buttermilk.
4. Pat steaks dry with paper towels and season with salt and pepper. Working with one steak at a time, drop into seasoned flour and turn to coat. Shake to remove excess flour, then dip in egg mixture and turn to coat.
5. Return to flour mixture and dredge a second time, shake off excess flour, and set on lined baking sheet. Repeat with remaining steaks.
6. In a Dutch oven or large stock pot, heat 1 inch oil to 375 degrees. Working in batches, fry steaks until deep golden brown all over, turning frequently, about 5 to 7 minutes.
7. Transfer to wire rack and place in oven. Return oil to 375 degrees and repeat with remaining steaks (do not discard fat). Keep warm in oven while making gravy.
8. To make the gravy:
9. Reserve 2 tablespoons oil from the pan and discard the rest (drain the oil through a fine-mesh sieve if desired). Reheat oil over medium-high heat until shimmering. Add onion, garlic, and thyme and cook until softened, about 4 to 5 minutes.
10. Whisk in flour until cooked through, about 1 minute. Whisk in broth, scraping up any brown bits off the bottom of the pan.
11. Whisk in milk, cayenne pepper, and salt and pepper to taste (I like ¾ teaspoon salt and ¼ teaspoon pepper). Bring to simmer over medium-high heat until slightly thickened, about 5 minutes. The gravy will thicken more as it cools.
12. Serve steaks warm with gravy on top and mashed potatoes on the side if desired.