Bring a medium pot of water to a boil and poach the shrimp for 2-3 minutes until pink and opaque, then immediately plunge into an ice bath to stop the cooking.
Once cooled, peel, devein, and chop the shrimp into bite-sized pieces.
In a large glass bowl, whisk together the lime juice, lemon juice, and extra virgin olive oil.
Add the finely diced red onion and minced jalapeño to the citrus mixture, letting it sit for 5 minutes to soften the sharp bite of the onion.
Fold in the chopped shrimp, diced cucumber, and diced tomato, ensuring all ingredients are thoroughly coated in the marinade.
Season the mixture with sea salt and black pepper.
Gently fold in the diced avocado and chopped fresh cilantro, taking care not to mash the avocado.
Chill the ceviche in the refrigerator for at least 15 minutes to allow the flavors to meld before serving.