Bring a large pot of salted water to a rolling boil. Add the rotini or shell pasta and cook according to package directions until al dente, about 8-10 minutes. Drain immediately in a colander.

Rinse the pasta thoroughly under cold running water until completely cooled. Allow it to drain well to prevent a soupy salad.

In a large mixing bowl, whisk together the mayonnaise, sour cream, and pickle juice until smooth and homogenous.

Add the chopped fresh dill, red onion, salt, and black pepper to the dressing. Stir well.

Gently fold in the chopped dill pickles and sharp cheddar cheese. Add optional bacon, green onions, or radishes if using.

Add the cooled pasta to the bowl with the dressing. Use a spatula to fold gently, ensuring every piece is coated.

Cover the bowl tightly with plastic wrap and refrigerate for at least 3 hours, preferably overnight, to allow flavors to meld.

Before serving, stir the salad. Adjust consistency with extra pickle juice or mayonnaise if needed. Serve chilled.