Boil rotini in water with the tablespoon salt until fully tender, about 10 to 12 minutes or according to the package. Drain thoroughly.
Whisk oil, vinegar, Dijon, oregano, dressing salt and pepper. Toss warm pasta with half the dressing and spread in a shallow dish for 10 minutes to stop steaming.
Transfer pasta to a large bowl and fold in bell pepper, celery, tomatoes, red onion and provolone with the remaining dressing.
Toss again and serve at cool room temperature, or cover and refrigerate promptly for at least 30 minutes for a colder salad.
Stir gently before serving and refrigerate leftovers within 2 hours.