In a medium bowl combine 1 cup ketchup, 2 tablespoons prepared horseradish, 1 tablespoon fresh lemon juice, 1 teaspoon Worcestershire sauce, 1 teaspoon hot sauce, 1 teaspoon freshly ground black pepper and 1 teaspoon salt.

Taste and adjust: add more horseradish for heat, more lemon for brightness, or more hot sauce for spice. If using, stir in 1 tablespoon finely chopped chives or parsley for color.

Cover and chill the sauce at least 30 minutes to let flavors meld (can be made up to 24 hours ahead).

Cooked Shrimp

Prepare poaching liquid

In a large pot combine 6 cups water, 2 teaspoons kosher salt, juice of the halved lemon (squeeze both halves), bay leaf and 6 peppercorns. Bring the liquid to a gentle boil over high heat.

Cook shrimp

Once the liquid reaches a rolling boil, add the 24 large shrimp in a single layer. Return to a gentle boil and cook until the shrimp are opaque and just curl, about 1.5 to 2 minutes depending on size. Do not overcook.

Shock shrimp

While the shrimp cook, prepare a large bowl with 4 cups ice and cold water. As soon as the shrimp turn opaque, use a slotted spoon to transfer them to the ice bath to stop cooking. Let cool completely, about 3 to 4 minutes.

Peel/finish

If shrimp are not already peeled/deveined, peel and remove the vein while leaving tails on for presentation. Pat shrimp dry with paper towels and refrigerate until ready to serve. Chill at least 15 minutes in the fridge so shrimp are cold when served.

Garnish & Serve

Portion: Arrange chilled shrimp on a platter over crushed ice or on individual cocktail glasses. Place a small bowl or ramekin of cocktail sauce in the center or inside each glass.

Garnish each serving with lemon wedges and a sprig of parsley or a few snipped chives. Serve immediately.

Make-ahead and storage

Cocktail sauce can be made up to 24 hours ahead and refrigerated. Cooked shrimp will keep covered in the refrigerator up to 2 days; keep chilled on ice while serving for best texture and food safety.