In a mixing bowl, combine mayonnaise, sour cream, lime zest, lime juice, dill, Dijon mustard, minced garlic, and a pinch of kosher salt. Stir until creamy and well-blended.

Fill a pot with water and bring to a boil. Add the shrimp and cook for 2-3 minutes until pink and opaque.

Transfer the cooked shrimp to a bowl of ice water for 3 minutes to chill.

In a large mixing bowl, add the cooled shrimp, diced cucumber, and sliced green onions. Pour the creamy dressing over and toss until evenly coated.

Serve immediately for best freshness, optionally garnished with extra dill or lime wedges.