Bring a small pot of water to a boil and blanch the shrimp for approximately 2 minutes until they are pink and opaque.
Immediately transfer the shrimp to a bowl of ice water to stop the cooking process, then drain and chop into bite-sized pieces.
In a large glass mixing bowl, whisk together the lime juice, lemon juice, extra virgin olive oil, sea salt, black pepper, and garlic powder to create the marinade.
Add the chopped shrimp to the bowl and toss thoroughly to ensure every piece is coated in the citrus dressing.
Stir in the diced Roma tomato, finely diced red onion, diced cucumber, and chopped fresh cilantro.
Gently fold in the diced avocado right before serving to keep the pieces intact and maintain a smooth, buttery texture.
Let the ceviche rest in the refrigerator for 10 to 15 minutes to allow the bright flavors to fully develop before serving chilled.