For the Shrimp:
Peel and devein shrimp leaving the tail on.
Add salt to a pot on the stove with the same amount of salt that you would add for pasta. Add the shrimp and turn on the heat. When the water is boiling and the top on the pot is showing some white foam on top. Check the shrimp and if cooked and not translucent, immediately drain the shrimp into a colander and immediately cover with ice. Rinse quickly to melt the ice and immediately drain to avoid drawing the shrimp. All this should only take less than ONE minute.
Refrigerate immediately at least a couple hours immediately until cold.
For the Cocktail Sauce:
Combine all ingredients; mix well to blend. Store in a covered jar or other covered container in the refrigerator. Chill thoroughly before serving.
Decorate a Martini glass with a lemon wedge and a spring of parsley.