01 - Preheat oven to 400°F or heat enough oil in a large skillet for shallow frying.
02 - Season fish pieces evenly with salt and black pepper on both sides.
03 - Arrange three shallow bowls: one with flour, one with beaten eggs, and one with combined panko breadcrumbs and cornmeal.
04 - Dredge each fish piece in flour, shaking off excess. Dip into egg wash, then press firmly into panko 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 through.
06 - Combine mayonnaise, chopped pickles, capers, lemon juice, Dijon mustard, and parsley in a mixing bowl. Refrigerate until ready to serve.
07 - Lightly toast slider bun halves until golden and warm.
08 - Place cooked fish fillet on bottom bun half. Top with cheese slice, lettuce, and generous spoonful of tartar sauce. Cover with top bun and serve immediately.