Make tartar sauce: Mix mayonnaise, pickle relish, lemon juice, and onion together and set aside.
Mix breadcrumbs, garlic powder, dried parsley, and parmesan cheese together.
Fish portions should be defrosted (if previously frozen). Dip each fish portion into water and then into bread crumb mixture.
Spray sheet pan with pan-release spray and place parchment paper onto pans. Spray parchment paper with spray and place fish onto pan. Spray more over the top of the fish and bake in a convection oven at 350°F until done. Place fish in a hot holding box and top with American cheese.
Mix shredded lettuce and diced tomato together in a bowl.
Spread a little tartar sauce on each side of the roll. Place 1/4 cup of the lettuce and tomato mixture on the bun. Buns can be prepared like this and placed onto sheet pans, which then can be placed on a sheet pan rack until service.
During service, place a fish portion on a bun and serve.
