Bring a large pot of salted water to a rolling boil. Add the rotini pasta and cook according to package directions until al dente. Drain and rinse under cold water.

While the pasta cools, prepare the vegetables: dice the cucumber, bell pepper, and onion, and halve the cherry tomatoes. Place all chopped vegetables in a large mixing bowl.

Add the cooled pasta to the bowl with the vegetables. Pour 1 cup of Italian dressing over the mixture, sprinkle in oregano and parsley, and toss thoroughly.

Gently fold in the crumbled feta cheese and sliced olives. Cover and refrigerate for at least 30 minutes before serving.