Cook the rotini pasta according to package instructions until al dente. Drain and rinse under cold water to cool.

In a large bowl, combine the cooled pasta, cucumber, cherry tomatoes, and red onion.

In a separate bowl, whisk together the mayonnaise, sour cream, apple cider vinegar, garlic powder, dried dill, salt, and pepper until smooth.

Pour the dressing over the pasta and vegetable mixture. Toss gently to combine until everything is well coated.

Cover the salad and refrigerate for at least 1 hour to allow the flavors to meld.

Before serving, give the salad a gentle stir and garnish with fresh dill if desired.