Pat the fish fillet dry with paper towels. Season both sides with 3/4 tsp salt and 1/2 tsp black pepper and drizzle 1 tbsp lemon juice over it. Let rest 5–10 minutes while you prepare other components.

Make tartar/sauce

In a small bowl combine 1/4 cup mayonnaise, 2 tbsp finely chopped dill pickles, 1 tsp chopped capers (if using), 1 tsp lemon juice, 1/2 tsp Dijon mustard, 1 tsp chopped fresh parsley, 1/8 tsp salt and a pinch (1/16 tsp) black pepper. Mix until smooth; taste and adjust seasoning. Chill until ready to assemble.

Make blackened seasoning (if selected)

Whisk together 1/2 tsp smoked paprika, 1/4 tsp garlic powder, 1/4 tsp onion powder, 1/8 tsp dried thyme, 1/8 tsp cayenne pepper, 1/4 tsp salt and 1/8 tsp black pepper in a small bowl. Set aside.

Cooking: Fried Option

Dredge fish

Mix 1/3 cup all-purpose flour, 1/4 cup cornmeal and 1/2 tsp paprika in a shallow dish. Lightly dredge the seasoned fillet, shaking off excess.

Fry fish

Heat 1/2 cup vegetable oil in a heavy skillet over medium-high heat until shimmering (about 350°F/175°C if using a thermometer). Add the fillet and fry 3–4 minutes per side (depending on thickness) until golden brown and cooked through (internal temp 145°F/63°C). Transfer to a wire rack or paper towel-lined plate to drain.

Cooking: Grilled Option

Oil and grill

Brush both sides of the seasoned fillet with 1 tsp olive oil. Preheat grill or grill pan to medium-high. Grill fish 3–5 minutes per side (depending on thickness) until opaque and easily flaked with a fork. Remove from heat and rest 1–2 minutes.

Cooking: Blackened Option

Apply blackened seasoning

Pat fish dry and press the prepared blackened seasoning onto both sides of the fillet to form an even coating.

Sear blackened fish

Heat a heavy skillet (cast-iron preferred) over high heat until very hot. Add a light brush of oil to the pan or the fish. Sear 2–3 minutes per side until a dark crust forms and the interior reaches 145°F/63°C. Reduce heat if crust is burning before fish cooks through.

Assemble & Serve

Toast bun: split the roll and spread 1 tbsp butter on cut sides. Toast in a skillet or under broiler until golden, about 1–2 minutes.

Build sandwich: Spread 1–2 tbsp tartar/sauce on bottom bun. Place lettuce leaf on sauce, then the hot fish fillet. Top with tomato slices and pickles (if using). Spread a little sauce on top bun and close sandwich.

Finish: Serve immediately with a lemon wedge and hot sauce on the side. For a fried fillet, let rest 1 minute after frying; for grilled/blackened, serve after the 1–2 minute rest. Recommended sides: fries, slaw, or salad.