01 - Preheat oven to 400°F or heat enough oil in a large skillet for shallow frying.
02 - Season fish pieces with salt and black pepper evenly on all sides.
03 - Set up three shallow bowls: one with flour, one with beaten eggs, and one with mixed panko and cornmeal.
04 - Dredge each fish piece in flour, dip in egg to coat completely, then press firmly into panko mixture to adhere.
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 parsley in a bowl. Mix thoroughly and refrigerate until serving.
07 - Lightly toast slider buns until golden and warm.
08 - Place a fish fillet on the bottom half of each bun. Top with cheese slice, lettuce, and a generous spoonful of tartar sauce. Cover with top bun and serve immediately.