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.
Adapted from Louisiana Real and Rustic by Emeril Lagasse