If shrimp is not pre-cooked, quickly blanch or sauté it until pink and opaque (about 2-3 minutes for pre-cooked shrimp to warm slightly). Drain well and set aside to cool completely.

Prepare the dressing: In a medium bowl, whisk together the mayonnaise, Greek yogurt, lemon juice, Dijon mustard, and garlic powder until smooth. Season generously with salt and freshly ground black pepper to taste.

Prepare the vegetables: Thinly slice the cucumbers and the red onion. If using standard cucumbers, consider salting them lightly for 10 minutes and patting them dry to remove excess water, preventing a watery salad.

Combine the main ingredients: In a large mixing bowl, gently combine the cooled shrimp, sliced cucumbers, thinly sliced red onion, and chopped fresh dill.

Dress and chill: Pour the prepared creamy dressing over the shrimp and vegetable mixture. Toss everything gently until evenly coated. Be careful not to break up the shrimp too much.

Refrigerate the salad for at least 30 minutes before serving to allow the flavors to meld. Serve chilled, perhaps over a bed of fresh lettuce or with crackers.