Dice the cucumbers into small, uniform cubes (about 1/4-inch). If using regular cucumbers rather than English or Persian, you may want to peel and seed them first.
Chop the tomatoes into pieces similar in size to the cucumber. For a less watery salad, you can remove the seeds before chopping.
Thinly slice or finely dice the red onion. To reduce sharpness, you can soak the sliced onion in ice water for 10-15 minutes, then drain and pat dry.
Combine the prepared cucumbers, tomatoes, and red onion in a large mixing bowl.
Finely chop the fresh parsley and mint, then add to the bowl with the vegetables. If using any optional vegetables like bell pepper, add them now.
In a small bowl, whisk together the olive oil, lemon juice, salt, and pepper until well combined.
Pour the dressing over the salad and gently toss until all ingredients are evenly coated.
Taste and adjust seasoning as needed, adding more salt, pepper, or lemon juice according to your preference.
If using optional toppings like feta cheese, sumac, or za'atar, sprinkle them on just before serving.
For best flavor, allow the salad to rest in the refrigerator for 15-30 minutes before serving to allow the flavors to meld together.
