1. In a medium bowl, combine shrimp, tomatoes, celery, fennel, lime juice, chili, and cilantro (optional).
2. Cover and refrigerate for at least 30 minutes or overnight.
3. To assemble: Spread bread equally with butter.
4. Place a Castello® Burger Blue Cheese slice on top of each piece of rye bread.
5. Divide the shrimp mixture equally between each sandwich.
6. Garnish with fresh ground black pepper and micro greens if desired.