1. Combine 1 1/2 gallons water and first 7 ingredients in a large Dutch oven, stirring well. Bring to a boil. Add shrimp, and cook over high heat 3 minutes or just until shrimp turn pink; drain.
2. Place shrimp immediately in a single layer over ice on a rimmed baking sheet. Let cool 5 minutes. Remove shrimp with tongs to a bowl; cover and chill.