Bring a medium pot of salted water to a boil, then add the peeled and deveined shrimp, poaching for 2-3 minutes until pink and opaque.
Drain the shrimp and immediately plunge them into an ice bath to stop the cooking process and ensure a tender texture.
Once the shrimp are completely cooled, chop them into bite-sized pieces and place them in a large glass mixing bowl.
In a small separate bowl, whisk together the lime juice, lemon juice, extra virgin olive oil, sea salt, and black pepper to create the marinade.
Add the diced cucumber, Roma tomato, finely diced red onion, and minced jalapeño to the bowl with the shrimp.
Pour the citrus marinade over the shrimp and vegetable mixture, tossing gently to ensure all ingredients are evenly coated.
Cover the bowl and refrigerate for at least 20 minutes to allow the bright, acidic flavors to penetrate the shrimp.
Just before serving, gently fold in the diced avocado and chopped fresh cilantro to maintain their color and creamy consistency.