Rinse the fillets and pat dry. In a large bowl, add roughly one cup of bread flour, or all purpose flour, and to that add one 12 oz. can of beer and stir to make a thick batter. If you want a thicker batter, add more flour. Add in a generous pinch of salt and pepper to season. This is where it gets a bit messy, so before diving in, heat a medium-sized pot with roughly four cups of oil and bring to a medium to high heat. You want the oil to reach about 375 degrees in temperature. In a separate bowl, add more flour, and season with more salt and pepper. Now it is time to get messy.
Take your dry fillet, one at a time, and place it in the batter. Carefully remove the fillet from the batter, letting any excess batter drip back into the bowl, and then place the fillet into the the bowl of seasoned flour, tossing to coat with the flour. Repeat witha couple of more fillets. When your oil is ready, add your fillet into the hot oil and cook until golden brown. Do not overcrowd the fillets..
When they are golden brown, remove to a strainer lined with paper towel, season with salt, and let cool. These will be piping hot.
Now to serve as a fish fillet sandwich, take your sliced but and add a generous amount of tartar sauce to the bottom bun. Top that with the sliced lettuce. Add on your fish fillet and top the fish with the cheese. Place on the top bun, and poke a couple of pickles with a toothpick if you desire. I like the pickles as they cut through some of the flavors of the fish and balance everything out.