Dice the cucumbers and tomatoes, and finely chop the red onion.

In a small bowl, whisk together olive oil, red wine vinegar, oregano, salt, and black pepper.

In a large mixing bowl, combine the diced cucumbers, tomatoes, and red onion. Pour the dressing over the salad and toss gently to combine.

Sprinkle chopped parsley over the salad before serving.