01 - Preheat oven to 400°F or heat 1/2 inch oil in a large skillet over medium-high heat for shallow frying.
02 - Pat fish pieces dry and season both sides evenly with salt and black pepper.
03 - Set up three shallow bowls: one with flour, one with beaten eggs, and one with panko breadcrumbs mixed with cornmeal.
04 - Dredge each fish piece in flour, shaking off excess. Dip into egg wash, then press firmly into panko mixture to coat evenly on all sides.
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 thoroughly and refrigerate until ready to serve.
07 - Lightly toast slider buns cut-side up for 2–3 minutes until golden.
08 - Place a crispy fish fillet on each bottom bun. Top with a cheese slice, lettuce, and a generous spoonful of tartar sauce. Cover with top bun and serve immediately.