Bring a medium pot of water to a boil and poach the peeled and deveined shrimp for 2 to 3 minutes until they are pink and opaque.
Drain the shrimp and immediately transfer them to a bowl of ice water to stop the cooking process and preserve their snap.
Once the shrimp are completely chilled, pat them dry and chop into bite-sized pieces, then place them in a large glass mixing bowl.
Squeeze the juice of the three limes over the shrimp and toss to coat, allowing them to marinate in the refrigerator for 15 minutes.
While the shrimp marinates, finely dice the red onion, cucumber, and roma tomato, and mince the jalapeño.
Remove the shrimp from the refrigerator and fold in the diced onion, cucumber, tomato, jalapeño, and chopped cilantro.
Gently stir in the diced avocado, taking care not to mash the pieces so they remain intact for texture.
Season the ceviche with sea salt and black pepper, tossing one last time before serving immediately in chilled bowls.