In a large pot, combine 3 cups water, kosher salt, bay leaves, peppercorns and the halved lemon (squeeze one half into the water then add the halves) and optional white wine. Bring to a gentle simmer over medium heat; do not boil vigorously.

Cook shrimp

Add the raw shrimp in a single layer to the simmering liquid. Cook until the shrimp are opaque and just firm, about 2 to 3 minutes for jumbo shrimp (16/20). Drain immediately.

Shock shrimp

Have a bowl prepared with 2 cups ice and 1 cup cold water. Transfer drained shrimp to the ice bath to stop cooking for 3 to 5 minutes, until completely chilled. Drain and pat shrimp dry, leaving tails on for presentation.

Store until serving

Keep the chilled shrimp refrigerated until ready to assemble the platter. If making ahead, cover and refrigerate up to 6 hours.

Cocktail Sauce

Mix sauce

In a bowl combine 1/2 cup ketchup, 2 tablespoons prepared horseradish, 1 tablespoon fresh lemon juice, 1 teaspoon Worcestershire sauce, 3 dashes hot sauce, smoked paprika, salt and pepper. Stir until smooth and taste; adjust horseradish for heat or lemon for brightness.

Chill

Cover and refrigerate the sauce at least 30 minutes to let flavors meld. It can be made a day ahead.

Garnish & Assembly

Prepare platter

Line a large serving platter or shallow bowl with crushed ice (about 4 cups) to keep shrimp cold. Mound the ice in the center or along the platter.

Arrange shrimp and sauce

Place a bowl or ramekin of chilled cocktail sauce in the center or at one end of the platter. Arrange the chilled shrimp around the bowl, tails facing out for easy pick-up. Add lemon wedges and sprinkle chopped parsley over the shrimp for color.

Serve

Serve immediately, with additional lemon wedges and extra cocktail sauce on the side. Keep the platter on ice if serving for longer than 20–30 minutes.