Dice the cucumbers and tomatoes, and thinly slice 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.

Garnish with crumbled feta cheese and chopped parsley before serving.