01 - Combine buttermilk and hot sauce in a shallow dish. Submerge fish fillets and let marinate for 15 minutes to tenderize and infuse flavor.
02 - Mix cornmeal, flour, Cajun seasoning, salt, black pepper, paprika, and cayenne in a large bowl until thoroughly blended.
03 - Pour vegetable oil to 1-inch depth in a large skillet. Heat to 350°F, maintaining steady temperature throughout frying.
04 - Remove fish from marinade, allowing excess liquid to drip off. Press each fillet into breading mixture, ensuring complete and even coating on all sides.
05 - Cook fish in batches, 3-4 minutes per side, until golden brown with crispy exterior and opaque, flaky interior. Transfer to paper towel-lined plate to drain excess oil.
06 - Whisk mayonnaise, chopped pickles, capers, lemon juice, Dijon mustard, parsley, salt, and pepper in small bowl until smooth. Refrigerate until ready to serve.
07 - Plate hot fish fillets immediately with chilled tartar sauce. Garnish with lemon wedges and serve alongside coleslaw or fries.