Bring 2 qt. water to a boil in a Dutch oven. Add shrimp, and cook 30 seconds. Drain, rinse under cool running water, and place in a small bowl.
Fill a medium bowl with ice. Place bowl containing shrimp in ice. Cover and chill 1 to 24 hours.
Squeeze juice from lemons through a small strainer over shrimp in a large bowl, drizzle with hot sauce, and toss to coat. Sprinkle with Creole seasoning, and toss to coat. Serve shrimp over mixed greens with Creamy Buttermilk-Avocado Sauce.