Pour 1 cup buttermilk over the shrimp so they are fully coated. Cover and refrigerate for 15–30 minutes. This tenderizes shrimp and helps the batter adhere.

Mix dry dredge

In a shallow dish or bowl, whisk together 1 cup all-purpose flour, 1/4 cup cornstarch, 1 tablespoon paprika, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1/2 teaspoon cayenne pepper, 1 teaspoon salt, and 1/2 teaspoon black pepper until uniform.

Dredge shrimp

Remove shrimp from the buttermilk in small batches, letting excess drip off. Dredge each shrimp in the seasoned flour mixture, pressing lightly so a thin, even coating sticks. Place dredged shrimp on a wire rack while you heat the oil.

Frying

Heat oil

Pour about 4 cups neutral oil into a heavy-bottomed pot or deep-fryer, filling to roughly one-third full. Heat the oil to 350°F (175°C). If you don't have a thermometer, test with one coated shrimp: it should sizzle immediately and the coating should start bubbling.

Fry shrimp

Fry the dredged shrimp in batches (do not overcrowd) for 1.5–2.5 minutes per batch, until the coating is golden brown and shrimp are opaque and just cooked through. Use a slotted spoon or spider to remove shrimp and transfer to a paper towel–lined baking sheet or wire rack. Keep cooked shrimp warm in a 200°F (95°C) oven if needed while frying remaining batches.

Drain and rest

Allow shrimp to drain 1–2 minutes; this keeps the bread from getting soggy when assembled.

Optional Remoulade

Make remoulade

In a small bowl whisk together 1/4 cup mayonnaise, 1 teaspoon Creole mustard, 1 tablespoon lemon juice, 1/2 teaspoon Worcestershire sauce, 1/2 teaspoon hot sauce, 1/4 teaspoon paprika, 1/4 teaspoon salt, and a pinch (1/8 tsp) black pepper until smooth. Taste and adjust seasoning. Refrigerate until assembly.

Poboy Build

Prepare bread

Split the 2 French rolls lengthwise without cutting all the way through if desired. Lightly toast cut sides in a hot skillet or under a broiler for 1–2 minutes until just golden (optional) to help resist sogginess.

Assemble spread

Mix the 1/2 cup mayonnaise with 2 tablespoons Creole mustard (or spread mayonnaise on both cut sides and mustard on one side). If using remoulade, spread a thin layer on both sides instead or in addition to mayonnaise.

Layer toppings and shrimp

On the bottom half of each roll, place shredded lettuce (about 1/2 cup per sandwich), sliced tomatoes, and 4 pickle slices. Pile the hot fried shrimp on top of the vegetables (about half the shrimp per sandwich so they are evenly distributed). If desired, sprinkle a few drops of hot sauce over the shrimp.

Finish and serve

Close the sandwich, press gently, cut each roll in half if serving two people, and serve immediately while shrimp are still hot and crisp.