Bring a pot of water to a boil, add the shrimp, and poach for 2 to 3 minutes until pink and opaque.
Immediately transfer the shrimp to an ice bath to stop the cooking process, then drain and chop into bite-sized pieces.
In a large glass bowl, whisk together the lime juice, lemon juice, sea salt, and black pepper.
Add the chopped shrimp, finely diced red onion, and minced jalapeño to the citrus mixture, tossing well to coat.
Gently fold in the diced cucumber, tomato, and avocado to maintain their structure.
Stir in the fresh cilantro and let the flavors meld in the refrigerator for 15 minutes before serving.