To keep shrimp well chilled place them in a bowl nestled inside a larger bowl of ice. Cook onion and garlic in olive oil in a large skillet over medium heat about 3 minutes or until tender. Add shrimp and tequila; bring to boiling. Boil gently, uncovered, 3-5 minutes or until shrimp turn pink, stirring occasionally. Transfer shrimp mixture to a bowl. Add lime juice, salt and cilantro. Toss to mix. Cover and refrigerate 2-24 hours stirring occasionally. Drain before serving. Serves 10-12.