Peel shrimp; devein, if desired.
Cook shrimp in boiling water to cover 3 to 5 minutes or just until shrimp turn pink; drain. Rinse with cold water.
Layer shrimp and onions in a large bowl. Whisk together oil and next 7 ingredients; pour over shrimp and onions. Cover and chill 24 hours, stirring occasionally. Stir in parsley just before serving.
Adapted from Charleston Receipts
Find recipes with ingredients that you have on hand.