Pulse first 4 ingredients in a food processor until chopped; add vinegar and next 4 ingredients. With processor running, add oil in a slow, steady stream.
Note: If you market doesn't steam shrimp as a service, buy 3 pounds unpeeled, jumbo fresh shrimp. Cook in 9 cups boiling water 3 to 5 minutes, or just until shrimp turn pink. Drain and rinse with cold water.