01 - Preheat oven to 400°F or heat enough oil in a large skillet for shallow frying.
02 - Season the fish pieces 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 and cornmeal.
04 - Dredge each fish piece in flour, shaking off excess. Dip in egg mixture, then coat thoroughly in panko-cornmeal mixture, pressing gently to adhere.
05 - For frying: Cook fish in batches for 2-3 minutes per side until golden brown and cooked through. For baking: Arrange on lined baking sheet and bake 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 until golden and warm.
08 - Place a crispy fish fillet on the bottom half of each bun. Add a cheese slice, lettuce, and a generous spoonful of tartar sauce. Top with the remaining bun halves and serve immediately.