In a large pot combine 3 liters of water, 2 tablespoons kosher salt, juice of the whole lemon plus the halved lemon shells, 2 bay leaves and 1 teaspoon black peppercorns. Bring to a gentle boil over medium-high heat.

Cook prawns

When the liquid reaches a rolling boil, add the prawns (do not overcrowd; cook in batches if necessary). Return to a boil and cook until the shells turn pink and the flesh is opaque and firm, about 2 to 3 minutes for jumbo prawns (timing depends on size).

Shock in ice bath

Meanwhile, prepare a large bowl with 4 cups of ice and cold water. As soon as prawns are cooked, use a slotted spoon to transfer them to the ice bath to stop cooking. Chill for at least 5 minutes until completely cool.

Peel and devein

Once cooled, peel the prawns leaving tails intact for presentation. Remove the vein with a small knife or deveiner, rinse briefly if needed, and pat dry on paper towels. Keep chilled until serving.

Spicy Cocktail Sauce

Combine 1 cup ketchup, 3 tablespoons prepared horseradish, 2 tablespoons fresh lemon juice, 1 teaspoon Worcestershire sauce and 1 teaspoon hot sauce in a medium bowl. Stir until smooth.

Add 1 teaspoon smoked paprika, 1 teaspoon chile flakes, 1 teaspoon sugar, 1 teaspoon sea salt and 1/2 teaspoon black pepper. Taste and adjust heat or acidity: add more horseradish for heat, more lemon for brightness, or a pinch more sugar to round flavors.

Cover and refrigerate the sauce for at least 30 minutes to let the flavors meld. Sauce will keep in an airtight container in the refrigerator up to 4 days.

To Serve

Arrange 6 lettuce leaves across a serving platter or individual cocktail glasses. Spoon 2 to 3 tablespoons of chilled cocktail sauce into small serving ramekins or the base of each glass.

Fan prawns around the ramekin or hang them on the rim of individual glasses with tails outward. Garnish with fresh lemon wedges and sprinkle 2 tablespoons sliced chives over the prawns and sauce.

Serve immediately, keeping extra prawns chilled on ice if not serving all at once.