Preparation Cook shrimp in a 5-quart pot of boiling salted water* until just cooked through, 2 to 3 minutes, then drain in a colander. Whisk together vinegar, oil, capers, salt, pepper, celery seeds, and Tabasco in a large bowl, then add warm shrimp, onion, celery, and bay leaves and toss to combine. Marinate, covered and chilled, 24 hours to 2 days. Just before serving, discard bay leaves. Quarter, pit, and peel avocados and cut into 3/4-inch cubes. Gently stir into shrimp salad, then spoon over lettuce. When salting water for cooking, use 1 tablespoon salt for every 4 quarts water.
Preparation Cook shrimp in a 5-quart pot of boiling salted water* until just cooked through, 2 to 3 minutes, then drain in a colander. Whisk together vinegar, oil, capers, salt, pepper, celery seeds, and Tabasco in a large bowl, then add warm shrimp, onion, celery, and bay leaves and toss to combine. Marinate, covered and chilled, 24 hours to 2 days. Just before serving, discard bay leaves. Quarter, pit, and peel avocados and cut into 3/4-inch cubes. Gently stir into shrimp salad, then spoon over lettuce. When salting water for cooking, use 1 tablespoon salt for every 4 quarts water.