Cook the pasta: Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente. Drain and rinse under cold water to cool.

Prepare the vegetables: While the pasta cooks, dice the cucumber, halve the cherry tomatoes, thinly slice the red onion, and halve the Kalamata olives.

Make the dressing: In a small bowl, whisk together the olive oil, red wine vinegar, dried oregano, salt, and black pepper.

Combine ingredients: In a large mixing bowl, add the cooled pasta, cucumber, cherry tomatoes, red onion, and Kalamata olives. Pour the dressing over the salad and toss gently to combine.

Add feta cheese: Sprinkle the crumbled feta cheese over the salad and gently toss again to distribute evenly.

Chill and serve: Cover the salad and refrigerate for at least 30 minutes before serving to allow the flavors to meld. Serve chilled.