01 - Preheat oven to 400°F or heat enough oil in a large skillet for shallow frying.
02 - Season the fish pieces evenly with salt and pepper on both sides.
03 - Set up three shallow bowls: one with flour, one with beaten eggs, and one with mixed panko breadcrumbs and cornmeal.
04 - Dredge each fish piece in flour, shaking off excess. Dip in egg mixture, then press firmly into panko-cornmeal mixture to coat thoroughly.
05 - Fry fish in batches for 2-3 minutes per side until golden brown and cooked through, or bake on a lined baking sheet for 10-12 minutes, turning once halfway.
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 in the oven or on a skillet cut-side up until golden.
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.