Before I started, I assumed jumbo shrimp were the biggest option out there, but Prime & Provisions (222 N. LaSalle St.) now serves what it refers to as a colossal shrimp cocktail. For $17 you get exactly one shrimp, which at first sounded like a crime I should report to the police until I realized that the one shrimp weighed a half-pound. “It took us a long time to find shrimp this big,” says Prime & Provisions’ chef Joseph Rizza. After looking around, he was able to find a fairly regular supply through Supreme Lobster, though he often has to order them in 500-pound shipments.