Le Fish Burger Recipe

Place the thinly sliced red onion in a heatproof bowl or jar.

Combine white wine vinegar, water, sugar and 1/2 tsp salt in a small saucepan and bring just to a simmer to dissolve the sugar.

Pour the hot pickling liquid over the onions, press them down so they're submerged, let cool to room temperature, then refrigerate at least 30 minutes (or up to overnight).

Cook eggs

Place 3 eggs in a saucepan, cover with cold water, bring to a gentle boil, then cook 9 minutes for hard-boiled yolks. Transfer to an ice bath, cool, peel, and separate whites from yolks. Finely chop whites and mash yolks.

In a medium bowl whisk together Dijon mustard, white wine vinegar and lemon juice. Slowly drizzle in the olive oil while whisking constantly to form a thick, stable emulsion (like a loose mayonnaise).

Fold the chopped egg whites and mashed yolks into the emulsion. Stir in capers, diced cornichons, parsley, chives and minced shallot. Season with 1/2 tsp salt and 1/4 tsp black pepper. Adjust to taste and refrigerate until assembly.

Pat the haddock fillets dry with paper towel and season both sides with 1 tsp salt and 1/2 tsp black pepper (use the amounts listed in Finishing & Seasoning and Fish & Coating combined). If fillets are thick, you may butterfly them or cut to uniform thickness (~3/4 inch) for even cooking.

Set up a breading station: one shallow dish with the flour, seasoned lightly with a pinch of salt and pepper; a second with the beaten eggs mixed with 1/4 cup milk; a third with the cornmeal or panko.

Dredge each fillet in flour (shake off excess), dip into the egg mixture, then press into the cornmeal/panko to coat evenly. Set on a rack for 5 minutes to let coating adhere.

In a large skillet, pour oil to come about 1/4 inch up the side and heat over medium-high until shimmering (about 350°F / 175°C). Carefully add fillets, working in batches so they do not crowd. Fry 3–4 minutes per side, until golden brown and cooked through (internal temperature 145°F / 63°C) and coating is crisp. Transfer to a paper towel-lined tray and keep warm in a low oven (200°F / 95°C) while finishing remaining fillets.

Split brioche buns and lightly butter the cut sides. Toast in a skillet or on a grill pan over medium heat until golden and crisp, about 1–2 minutes per side.

On the bottom bun spread a generous tablespoon of gribiche (adjust to preference). Place two bibb lettuce leaves on top to create a cushion.

Place a hot fried haddock fillet on the lettuce. Spoon 1 to 2 tablespoons of gribiche on top of the fish, add a few pickled onion slices, and a grind of black pepper and a light pinch of salt if needed.

Crown with the top bun and press gently. Serve immediately with a lemon wedge for squeezing over the fish.

Taste one sandwich and adjust salt/pepper or extra gribiche on the side. Serve 4 fish burgers with remaining gribiche and pickled onions on the side.