Bring a medium pot of water to a boil and poach the shrimp for 2 to 3 minutes until they are pink and opaque.
Drain the shrimp and immediately plunge them into an ice bath for 5 minutes to stop the cooking process and ensure a firm texture.
Peel and devein the shrimp if necessary, then chop them into bite-sized pieces and place in a large glass bowl.
Finely dice the Roma tomato, red onion, and jalapeño, then add them to the bowl with the shrimp and chopped cilantro.
In a small jar, whisk together the lime juice, lemon juice, extra virgin olive oil, sea salt, and black pepper.
Pour the citrus dressing over the shrimp mixture and toss thoroughly to combine the flavors.
Gently fold in the diced avocado just before serving to maintain its buttery consistency and prevent mashing.
Let the ceviche sit for 10 minutes in the refrigerator to allow the citrus to fully marinate the ingredients before enjoying.