Prepare the shrimp by peeling, deveining, and blanching in boiling water for 2 minutes until pink, then immediately plunging into ice water to stop the cooking.
Chop the cooled shrimp into half-inch bite-sized pieces and place them in a large glass mixing bowl.
In a small jar or bowl, whisk together the lime juice, lemon juice, and extra virgin olive oil.
Finely dice the red onion, cucumber, and tomato, then add them to the bowl with the shrimp.
Mince the jalapeño after removing the seeds and finely chop the fresh cilantro, adding both to the mixture.
Pour the citrus dressing over the ingredients and season with sea salt and black pepper, stirring gently to combine.
Dice the avocado into small cubes and carefully fold them into the ceviche to maintain their shape.
Cover and refrigerate for at least 15 minutes before serving to allow the flavors to meld and the dish to reach a crisp, chilled temperature.