Peel, devein, and chop the raw shrimp into bite-sized pieces.
Place the shrimp in a glass bowl and pour the lime and lemon juices over them until the shrimp are completely submerged.
Cover the bowl and refrigerate for 30 to 45 minutes, or until the shrimp turn opaque and firm.
While the shrimp cures, finely dice the red onion, cucumber, and roma tomato.
Remove the seeds from the jalapeño and mince it finely, then chop the fresh cilantro.
Once the shrimp is ready, drain about half of the citrus juice from the bowl.
Stir in the diced onion, cucumber, tomato, jalapeño, and cilantro.
Gently fold in the diced avocado to keep the pieces intact.
Season with sea salt and black pepper, then drizzle with olive oil and toss lightly before serving.