Squeeze the juice from the lemons into a large pot. Add the halves. Add the water, bay leaves, salt cayenne, and crab boil. Bring to boil and cook for 5 minutes. Add the shrimp. Remove from the heat, cover, and let stand for 4 to 5 minutes. Drain. Serve either cooled or chilled completely. Combine the remaining ingredients in a food processor with a metal blade and process for 30 seconds. Use immediately or store. Will keep for several days in an airtight container in the refrigerator.