Boil a large pot of salted water and cook fusilli pasta according to package directions until al dente, then drain and rinse under cold water to cool.

If using frozen peas, briefly blanch them in boiling water for two minutes, then rinse with cold water.

In a large mixing bowl, whisk together mayonnaise, sour cream, apple cider vinegar, salt, and black pepper to create the creamy dressing.

Add the cooled fusilli, green peas, chopped red onion, beef bits, and fresh parsley to the bowl with the dressing.

Toss everything gently until the pasta and vegetables are evenly coated with the dressing, then cover and refrigerate for at least thirty minutes before serving.