In a medium mixing bowl, combine the dry Ranch Dressing Mix, mayonnaise, and sour cream. Whisk together until smooth. Cover with plastic wrap and refrigerate for 30 minutes to let flavors meld.
Cook the rotini pasta according to package directions. Drain, rinse under cold water, and drain again thoroughly.
In a large mixing bowl, combine the pasta, chopped bacon, red onion, cheddar cheese, avocado, cherry tomatoes, parsley, and romaine lettuce.
Pour the chilled dressing over the salad ingredients. Gently toss everything together with tongs until well coated and evenly distributed.
Serve immediately and enjoy!