01 - Cook the macaroni according to package instructions until al dente. Drain and rinse under cold water; set aside to cool.
02 - In a large bowl, whisk together mayonnaise, sour cream (or Greek yogurt), lemon juice, Dijon mustard, garlic powder, salt, and pepper until smooth.
03 - Add cooled macaroni, shrimp, celery, red bell pepper, red onion, and dill (or parsley) to the bowl with the dressing.
04 - Gently toss until all ingredients are evenly coated.
05 - Cover and chill in the refrigerator for at least 1 hour before serving for best flavor.
06 - Stir again before serving. Adjust seasoning if needed.