Boil the pasta in salted water according to package directions. In the last 2 minutes of cooking, add the broccoli florets to blanch them. Drain and rinse under cold water to stop the cooking process.

In a large mixing bowl, whisk together the mayonnaise, sour cream, apple cider vinegar, black pepper, and salt until smooth.

Add the cooled pasta, blanched broccoli, and diced cooked beef to the bowl with the dressing. Toss gently until all ingredients are evenly coated.

Cover the bowl with plastic wrap and chill in the refrigerator for at least 2 hours before serving to allow the flavors to meld.