In a medium bowl, combine mayonnaise, sour cream, lime zest and juice, dill, Dijon mustard, and minced garlic. Whisk together until smooth and creamy, then refrigerate for about 15 minutes.

Fill a medium pot with water, add a pinch of salt, and bring to a boil. Carefully add the shrimp and cook for 2-3 minutes until bright pink and opaque. Remove from heat.

Prepare an ice water bath and transfer cooked shrimp into it for 3 minutes to cool and stop cooking. Drain and set aside.

In a large mixing bowl, combine cooled shrimp, chopped cucumber, and green onions. Fold in the creamy dressing and toss until all ingredients are coated.

Serve immediately or chill in the fridge for 10-15 minutes before serving. Garnish with additional dill if desired.