Rinse all produce thoroughly under cold running water.
Dice the English cucumbers into half-inch cubes.
Chop the Roma tomatoes into sizes that match the cucumbers for consistent bites.
Thinly slice the red onion to ensure a milder flavor profile.
In a large mixing bowl, combine the diced cucumbers, tomatoes, red onions, and pitted olives.
In a small separate bowl, whisk together the olive oil, red wine vinegar, and dried oregano.
Pour the dressing over the vegetable mixture and toss gently to coat evenly.
Top with crumbled feta cheese right before serving and garnish if desired.