In a small bowl, whisk together mayonnaise, sour cream, sweet pickle relish, white vinegar, salt, pepper, and dried dill.
Set the dressing aside.
Cook rotini pasta al dente according to the package directions.
Drain the pasta and rinse it under cold water to stop the cooking process. Allow the pasta to drain completely.
In a large mixing bowl, combine the cooked pasta, drained canned tuna, diced celery, sliced green onions, defrosted and drained frozen peas, and diced cheddar cheese if using.
Pour the prepared dressing over the pasta mixture and stir until everything is evenly coated.
Cover and refrigerate the pasta salad for at least 1 hour before serving.