If you're using raw shrimp, bring a pot of salted water to a gentle boil. Add the shrimp and cook until they turn opaque and pink — about 2 to 3 minutes. Immediately remove them with a slotted spoon and transfer to a bowl of ice water to stop the cooking process. Once cooled, chop the shrimp into bite-sized pieces. If you're using pre-cooked shrimp, simply chop and set aside.

In a large bowl, combine the chopped red onion, peeled and diced cucumber, chopped celery, and minced jalapeño. Toss gently to mix.

Add the chopped shrimp to the vegetable mixture and stir well to combine. Cover the bowl and refrigerate for at least 1 hour. This helps the flavors come together and gives the dish its signature chilled zing.

Spoon into small bowls or cocktail glasses. Top with avocado slices if desired and serve cold.