To make a simple shrimp cocktail sauce, whisk together 1/2 cup ketchup, 2 tablespoons horseradish, 1 teaspoon of lemon juice, 1/2 teaspoon of Worcestershire sauce, 1/2 teaspoon hot sauce in a bowl, then transfer sauce into serving bowl. Poach 2 pounds peeled and deveined jumbo shrimp, in boiling water, pan fry them on stovetop or roast in an oven until opaque. Serve hot or cold.
Alternatively, prepare the poaching liquid by stirring in 12 cups of cold water, 1/4 sliced onion, 1/2 lemon, 2 cloves of garlic, peeled and bruised, 2 sprigs fresh tarragon, 1 tablespoon of seafood seasoning, 1 teaspoon whole black peppercorns and 1 bay leaf into a large pot. Simmer and cook for 15 minutes until flavors blend.
To make the sauce, whisk 1/2 cup ketchup, 1/4 cup chili sauce, 1/4 cup prepared horseradish, 1 teaspoon of lemon juice, 1 teaspoon Worcestershire sauce, 3 drops hot sauce, and 1 pinch salt into a bowl. Refrigerate for 15 minutes until chilled.
Bring the poaching liquid to a boil, and cook 2 pounds shell-on deveined jumbo shrimp in the boiling liquid they turn bright pink and the meat isn't visible in the centre. Put the shrimp into a bowl of ice-cold water, immerse into another bowl of ice water until cold, and drain. Place the shrimp on a platter, and serve with chilled sauce.