In a large mixing bowl, combine the sliced cucumber, diced tomatoes, and thinly sliced red onion. Drizzle the olive oil and red wine vinegar over the vegetables, then season with salt and pepper. For an extra burst of flavor, toss in some freshly chopped herbs like parsley, basil, or dill, if desired. Gently mix everything together until well coated. Cover the bowl and refrigerate for at least 20 minutes before serving to allow the flavors to meld. Enjoy this salad chilled.