Cook the macaroni pasta in salted water according to package instructions until al dente. Drain and set aside to cool.
Dice the red onion, red bell pepper, celery, and green onion. Mince the parsley and dill. Set all vegetables aside.
In a separate bowl, whisk together the mayonnaise, sour cream, Dijon mustard, apple cider vinegar, brown sugar, garlic powder, black pepper, and salt until smooth.
In a large bowl, combine the cooled macaroni, diced vegetables, and herbs. Mix well.
Pour the dressing over the pasta mixture and gently combine until everything is evenly coated.
Cover with plastic wrap and refrigerate for at least 2 hours before serving.
Notes
For best flavor, let the salad sit in the fridge longer than 2 hours if possible.