Pat the fish dry and season both sides with salt.
Mix all your batter ingredients in a bowl (flour and seasonings) and then mix in your club soda to make it a batter.
Dredge fish in bowl of regular unseasoned flour, then dip into wet batter mix, and then place in your oil to fry.
Fry at 350°F until golden brown and the fish reaches an internal temperature of 145°F, about 4–6 minutes per side depending on thickness. Drain on a wire rack.
Mix together all of the sauce ingredients until smooth.
Toast the brioche buns, spread the sauce on both sides, then layer with sauce, lettuce, crispy fish, american cheese, sauce and the top bun.
