01 - Preheat oven to 400°F or heat enough oil in a large skillet for shallow frying.
02 - Season fish pieces with salt and pepper on all sides.
03 - Arrange 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, shake off excess, dip in egg mixture, then coat thoroughly with panko-cornmeal mixture.
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.
06 - Combine mayonnaise, chopped pickles, capers, lemon juice, Dijon mustard, and parsley in a mixing bowl. Refrigerate until serving.
07 - Lightly toast slider buns until golden brown.
08 - Place a fish fillet on the bottom half of each bun, top with a cheese slice, lettuce, and a generous spoonful of tartar sauce. Cover with bun tops and serve immediately.