Combine 1/2 cup mayonnaise, 1/4 cup sour cream, the zest and juice of 1 lime, 1 tablespoon chopped dill, 1 teaspoon Dijon mustard, and 1 minced garlic clove in a medium bowl. Season with salt and pepper. Chill for 15 minutes.

Bring a pot of salted water to a boil. Add 1 pound shrimp and cook for 2-3 minutes until pink and opaque. Remove from heat.

Transfer shrimp to ice water to stop cooking for 5 minutes. Drain and pat dry, then chop into bite-sized pieces.

In a large mixing bowl, add chopped shrimp, diced cucumbers, and sliced green onions. Drizzle with the chilled dressing and fold to combine.

Chill for at least 10 minutes before serving to enhance flavors.