In a large bowl, combine the diced tomatoes, cucumber, red bell pepper, and finely chopped onion.
Add the crumbled feta cheese and chopped parsley to the bowl with the vegetables.
In a small bowl, whisk together the olive oil, red wine vinegar, salt, and black pepper.
Pour the dressing over the vegetable and cheese mixture. Toss gently to combine everything well.
If using, add black olives on top of the salad for extra flavor.
Enjoy your meal!