Bring a large pot of water to a boil and poach the peeled and deveined shrimp for 2-3 minutes until they are pink and opaque.
Immediately drain the shrimp and transfer them to an ice bath for 5 minutes to stop the cooking process and ensure a firm texture.
Once chilled, pat the shrimp dry and chop them into bite-sized pieces, then place them in a large glass mixing bowl.
Whisk together the lime juice, olive oil, chili powder, sea salt, and black pepper in a small ramekin before pouring over the shrimp.
Add the diced cucumber, finely diced red onion, minced jalapeño, and chopped cilantro to the bowl and toss thoroughly to combine.
Gently fold in the diced avocado, being careful not to mash the pieces, so they provide a creamy contrast to the crisp vegetables.
Cover and refrigerate for at least 15 minutes before serving to allow the citrus and spices to fully penetrate the shrimp.