Bring a large pot of salted water to a boil. Add the rotini pasta and cook according to package directions until al dente, about 8-10 minutes.
Drain the pasta and rinse under cold water to stop the cooking process. Set aside to cool completely.
In a medium bowl, whisk together mayonnaise, sour cream, apple cider vinegar, Dijon mustard, garlic powder, salt, and pepper until smooth.
In a large mixing bowl, combine the cooled pasta, cherry tomatoes, cucumber, red onion, black olives, and parsley.
Pour the dressing over the pasta mixture and toss gently until everything is evenly coated.
Cover the bowl and refrigerate for at least 1 hour to allow the flavors to meld. Stir before serving.