Make the tartar sauce. Add all tartar sauce ingredients to a bowl and mix until combined. Season with salt and mix again, tasting and adding more salt if needed.

Bread the fish. To three wide, shallow dishes, add the flour, egg and pickle brine, and finely crushed bran flakes. Season all three with salt and a pinch of cayenne, then mix/whisk all three separately until well combined. Pat your fish filets dry and season both sides of each filet with salt, then dredge in the flour, coating evenly and shaking off any excess. Repeat with the egg, then add to the crushed bran flakes and gently press the coating onto the fish on all sides. Repeat with the remaining filets, then set aside and let rest for about 10 minutes to help the breading stick to the fish.

Heat a large skillet over medium low heat for 5 minutes, then add 2 tsp of oil. When the oil shimmers, add 2 pieces of fish and tilt the pan so the oil bubbles all around each filet. Pan fry each side on medium low heat for 3-5 minutes, then add 2 more tsp of oil, flip and repeat on the other side, until the filets are golden brown, crispy, and cooked to about 140°F. Top each filet with a slice of American cheese and transfer the cooked filets to a paper towel to pat off any excess oil, then set on a cooling rack. While the fish is resting for a few minutes, the residual heat will help melt the cheese and continue cooking them to the safe 145°F eating temp.

While the fish is resting, toast your buns. To the same skillet, add a tsp of oil (I like to use spray oil for this to reach the most surface area for less fat) and turn the heat to medium high. Once hot and the oil shimmers, add two buns (4 halves) cut side down and gently press to get more of the bun surface on the pan. Toast until golden brown and slightly charred, about a minute, then remove and repeat with the other 2 buns.

Assemble each sandwich by spreading a heaping tablespoon of tartar sauce onto each toasted bun halve, then top each bottom bun with a cheesy filet, and crown each with a tartar-shmeared top bun. Enjoy immediately!