Bring a medium pot of water to a boil and poach the peeled 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 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.
In a small jar, whisk together the lime juice, olive oil, chili powder, sea salt, and black pepper until well combined.
Add the diced cucumber, tomato, red onion, minced jalapeño, and chopped cilantro to the bowl with the shrimp.
Pour the dressing over the shrimp mixture and toss gently to ensure everything is evenly coated.
Carefully fold in the diced avocado just before serving to prevent it from mashing.
Let the ceviche sit in the refrigerator for 10 to 15 minutes to allow the flavors to fully develop before enjoying.