In a medium mixing bowl, combine mayonnaise, sour cream, lime zest, lime juice, dill, mustard, minced garlic, salt, and pepper. Whisk together until smooth and creamy.

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

Prepare an ice bath. Transfer the cooked shrimp to the ice bath for 3 minutes to cool.

In a large mixing bowl, add the chopped shrimp, sliced green onions, and diced cucumbers. Pour the chilled dressing over and gently toss.

Transfer to a serving bowl and chill for 10-15 minutes before serving.