Begin by gathering a large serving bowl. Slice the Persian cucumbers into thin rounds, then add them to the bowl. Pour in the fresh lemon juice, sprinkle the chopped parsley leaves, ground sumac, and kosher salt over the cucumbers. Finally, drizzle the extra-virgin olive oil, ensuring all ingredients are ready to combine for this refreshing sumac cucumbers salad.

Using your clean hands, gently massage the cucumber mixture for about 2 to 3 minutes. As you do this, you'll notice the cucumbers start to release their juices, mixing harmoniously with the other ingredients.

Once the salad is well-mixed, cover the bowl with a lid or plastic wrap to trap the flavors. Allow the cucumber mixture to marinate for 30 minutes at room temperature.

After marinating, give the salad a gentle stir to combine any settled ingredients. Taste a cucumber slice and adjust the seasoning if needed. Serve the sumac cucumbers salad chilled or at room temperature.