Begin by bringing a large pot of salted water to a rolling boil. Add the rotini pasta and cook according to the package instructions until al dente, about 8-10 minutes. Once cooked, drain the pasta in a colander and rinse it under cold water.

While the pasta is cooking, wash and finely chop the cherry tomatoes, cucumber, bell pepper, and red onion. Thaw the frozen peas under warm water. Combine all vegetables in a large mixing bowl.

In a medium bowl, whisk together the mayonnaise, sour cream, apple cider vinegar, sugar, salt, and black pepper until smooth. Taste and adjust seasonings as necessary.

Add the cooled rotini pasta to the large bowl with the chopped vegetables. Pour the creamy dressing over the ingredients and gently toss until evenly coated.

Cover the bowl with plastic wrap or transfer to an airtight container. Refrigerate for at least 1 hour before serving to allow flavors to meld.