Mahi Mahi Sandwich Recipe

Prepare fish

Pat the mahi mahi fillets dry with paper towels. If the fillets are thick, cut into four even portions (about 4 ounces each). Season both sides lightly with 0.5 tsp of the salt and 0.25 tsp of the black pepper listed in the Seasoning & dredge section.

Slice the tomato into 4 even slices. Thinly slice 1/4 red onion into rings. Tear or wash 4 romaine leaves and set aside. Halve the lemon; reserve one half for squeezing and slice the other half into wedges for serving.

Split buns and toast cut sides lightly in a dry skillet or under the broiler for 1–2 minutes until golden. Set toasted buns aside.

Make the dry mix: in a shallow dish combine 1/2 cup all-purpose flour, 2 tsp cornstarch, 1 tsp paprika, 1/2 tsp garlic powder, 1/2 tsp onion powder, 1 tsp salt, and 1/2 tsp black pepper. Mix thoroughly.

Make the wet mix: in a separate shallow bowl whisk 1 large egg, 2 tbsp milk, and 1 tsp hot sauce (if using) until combined.

Dredge each seasoned mahi mahi piece first in the dry mix, shaking off excess, then dip in the wet egg mixture, and finally return to the dry mix for a light double coating. Place coated pieces on a plate while you heat the pan.

Heat a large skillet over medium-high heat and add 2 tbsp oil and 1 tbsp butter. When the butter stops foaming and the oil is shimmering, add the coated mahi mahi pieces (do not overcrowd; cook in batches if necessary).

Cook for 3–4 minutes per side depending on thickness, until the crust is golden-brown and internal temperature reaches 137–140°F (58–60°C) and the fish flakes easily with a fork. Total cook time per piece ~6–8 minutes. Transfer cooked fish to a wire rack or plate and tent loosely with foil to keep warm.

Make the sandwich spread: in a small bowl mix 1/2 cup mayonnaise, 1 tsp Dijon mustard, 1 tsp chopped capers (if using), 1/4 tsp salt, and 1/8 tsp black pepper. Taste and adjust seasoning or add a squeeze of lemon juice from the reserved lemon half if desired.

Build sandwiches: spread about 1.5 tbsp of the mayonnaise mixture on each bottom bun. Place a romaine leaf, then a cooked mahi mahi piece, top with a tomato slice, a few red onion rings, and 2 pickle slices (if using). Squeeze a little fresh lemon juice over the fish, then cap with the toasted top bun.

Serve immediately with lemon wedges on the side.