Preheat the oven to 450 degrees F. Line a large rimmed baking sheet with parchment paper. Pour the shrimp onto the baking sheet and drizzle with 1 tablespoon olive oil. Toss the shrimp in the oil and spread them out on the baking sheet. Sprinkle generously with salt and pepper.

Roast the shrimp in the oven for 5-7 minutes, until pink. They should still be in the shape of C's. If they shrink to O's, you've overcooked them. Cool the shrimp on the baking sheet.

Meanwhile, chop the cucumber and avocado in ¾-inch chunks. Place the cucumber, avocado, minced garlic, chopped mint leaves, and cilantro in a salad bowl. Pour the lime juice and 1 tablespoon olive oil over the salad and toss well to coat. Taste, then salt and pepper as needed.

Once the shrimp have cooled to room temperature, toss them into the salad. Cover and chill until ready to serve.