1. Whisk together olive oil, balsamic vinegar, and next 5 ingredients in a large bowl.
2. Place cooked shrimp and vinaigrette mixture in a large zip-top plastic freezer bag. Seal and chill at least 8 hours or up to 24 hours, turning bag occasionally.
3. Arrange lettuce leaves in 8 (6- to 8-oz.) glasses. Spoon shrimp mixture evenly into glasses.
Note: Vinaigrette may be prepared ahead and stored in an airtight container in the refrigerator up to 1 week. Let vinaigrette come to room temperature, and whisk before adding cooked shrimp.