Begin by boiling a large pot of salted water on high heat. Add the rotini or medium pasta and cook according to package instructions, usually around 8-10 minutes, until al dente. Drain and rinse under cold water for about 30 seconds.

Chop the cucumber, grape tomatoes, bell pepper, and onions into bite-sized pieces.

In a large mixing bowl, combine the cooled pasta, chopped vegetables, and Italian dressing. If using, add black olives.

Season with salt and black pepper to taste, and gently fold in crumbled feta cheese.

Cover the bowl with plastic wrap or transfer to an airtight container and refrigerate for at least 2 hours before serving.