How to Make It
Make Cocktail Sauce: Stir ingredients together until combined. Refrigerate until ready to serve.
Make Poached Shrimp: Bring vegetable stock to a boil in a heavy-bottomed pot with a lid. Add garlic, parsley, bay leaves, and peppercorns. Cover with lid and boil gently for 30 minutes.
In a large bowl prepare an ice bath; set aside. Using tongs or a slotted spoon, discard garlic head, lemon halves, and parsley from the boiling liquid. Bring liquid back to a boil and then remove from heat. Immediately submerge shrimp in liquid, cover with lid, and allow shrimp to cook for 2 1/2 to 3 minutes, until the flesh turns pink and the shrimp curl slightly. Strain shrimp and submerge in prepared ice bath for 1 minute; strain. Allow to cool to room temperature before peeling, leaving the tails on. Remove the vein if desired. Serve immediately with Cocktail Sauce or refrigerate.