Bring a medium pot of salted water to a boil.
Add the shrimp and poach for 2-3 minutes until they are pink and opaque.
Drain the shrimp and immediately plunge them into an ice bath to stop the cooking process.
Once cooled, pat the shrimp dry and chop them into bite-sized pieces.
In a large glass bowl, whisk together the lime juice, lemon juice, orange juice, olive oil, sea salt, and black pepper.
Add the chopped shrimp, finely diced red onion, and minced jalapeño to the citrus marinade, stirring well to coat.
Gently fold in the diced cucumber, seeded roma tomato, and cubed avocado to maintain their shape and texture.
Garnish with chopped fresh cilantro and let the ceviche sit for 10 minutes in the refrigerator before serving chilled.