Prepare the vegetables: Wash and dice the tomatoes and cucumber into bite-sized pieces. Thinly slice the red onion.
Combine the main ingredients: In a large mixing bowl, combine the diced tomatoes, cucumber, and red onion. Add the Kalamata olives and cubed feta cheese.
Add the herbs: Chop fresh parsley and mint and sprinkle them over the ingredients. Add dried oregano as well.
Dress the salad: Drizzle olive oil and red wine vinegar over the salad. Season with salt and pepper to taste.
Toss and serve: Gently toss the ingredients together until well combined. Serve immediately or chill for about 30 minutes to allow the flavors to meld.