Wash the cucumbers and tomatoes thoroughly.
Slice the cucumbers into thin rounds.
Chop the tomatoes into bite-sized pieces.
Thinly slice the red onion.
In a large mixing bowl, combine the sliced cucumbers, chopped tomatoes, and red onion.
Add the crumbled feta cheese to the bowl.
In a small bowl, whisk together the olive oil and balsamic vinegar.
Pour the dressing over the salad mixture.
Toss gently to combine, ensuring everything is evenly coated.
Season with salt and pepper to taste, and garnish with fresh parsley before serving.