In a bowl, combine mayonnaise, sour cream, lime zest and juice, dill, mustard, garlic, salt, and pepper. Mix well and set aside.

Boil water in a pot; add shrimp and cook for 2-3 minutes until pink and opaque.

Transfer cooked shrimp to an ice water bath to halt cooking; cool for about 3 minutes before draining.

In a large bowl, mix cooled shrimp with diced cucumber, green onions, and dressing until evenly coated.