Cook the Ziti Pasta in salted water according to package instructions until al dente, then rinse under cold water and drain well.

Finely dice the red onion, red bell pepper, and celery; combine in a large mixing bowl and sprinkle with celery salt and celery seed.

Grate the carrot, chop further into small pieces, and add to the vegetable mixture.

Whisk together mayonnaise, sour cream, celery seed, and salt in a medium bowl until smooth.

If using fresh parsley, mince and add to the vegetable mixture; let it sit for about 15 minutes.

Combine the cooked pasta and creamy dressing with the vegetable mixture, gently tossing to coat.

Fold in the diced cheddar cheese gently to ensure even distribution.

Transfer to an airtight container and refrigerate for at least 4 to 6 hours or ideally overnight.