In a large pot combine 2 liters of water, kosher salt, bay leaf and black peppercorns. Slice the lemon in half and squeeze one half into the pot, then add the squeezed lemon halves as well. Bring the liquid to a gentle boil over high heat.

Poach shrimp

Once the poaching liquid reaches a gentle rolling boil, reduce heat so the liquid is at a steady simmer. Add the shrimp in a single layer and cook until they turn pink and just curl, about 2 to 3 minutes depending on size (16–20 shrimp will cook quickly). Do not overcook — shrimp are done when opaque and the tails curl into a loose C.

Shock shrimp

While shrimp cook, fill a large bowl with 4 cups of ice and cold water to make an ice bath. As soon as shrimp are cooked, immediately transfer them with a slotted spoon to the ice bath to stop cooking. Let chill until completely cold, about 3–5 minutes.

Dry and refrigerate

Remove shrimp from the ice bath and drain thoroughly on paper towels. Pat dry and arrange on a plate; refrigerate until ready to serve. Keep tails on for presentation and easier dipping.

Cocktail Sauce

Combine ketchup, prepared horseradish, fresh lemon juice, Worcestershire sauce, hot sauce, smoked paprika, salt and freshly ground black pepper in a medium bowl.

Taste and adjust seasonings: add more horseradish for heat, more lemon for brightness, or a dash more hot sauce if you prefer spicier. Chill the sauce in the refrigerator at least 15 minutes to let flavors marry (can be made up to 2 days ahead).

Garnish & Serving

Prepare serving platter by filling a shallow bowl or platter with 6 cups of crushed ice. Arrange chilled shrimp on top of the ice, tails outward for easy picking, or hang shrimp around the rim of individual cocktail glasses.

Spoon cocktail sauce into a small bowl and place it in the center of the shrimp arrangement. Garnish with lemon wedges and chopped parsley.

Serve immediately. Provide small forks or cocktail picks and extra lemon wedges at the table.