01 - Preheat oven to 400°F or heat oil in a large skillet for shallow frying.
02 - Season fish pieces thoroughly with salt and pepper on all sides.
03 - Prepare three shallow bowls: one with flour, one with beaten eggs, and one with panko mixed with cornmeal.
04 - Dredge each fish piece in flour, shaking off excess. Dip into egg mixture, then press firmly into panko mixture to coat completely.
05 - Fry fish in batches for 2-3 minutes per side until golden and cooked through, or bake on a lined baking sheet for 10-12 minutes, turning once halfway through.
06 - Combine mayonnaise, chopped pickles, capers, lemon juice, Dijon mustard, and fresh parsley in a bowl. Mix well and refrigerate until serving.
07 - Lightly toast slider buns for added texture and to prevent sogginess.
08 - Place a cooked fish fillet on the bottom half of each bun. Top with a cheese slice, lettuce, and a generous spoonful of tartar sauce. Cover with top bun and serve immediately.