Dice the tomatoes, Persian cucumbers, green bell peppers, and red onion into small, uniform cubes about 3/8-inch in size. Transfer all chopped vegetables and the fresh parsley to a large salad bowl.

Sprinkle the ground sumac and fine sea salt evenly over the vegetables. Toss lightly to distribute the spices.

Drizzle the extra virgin olive oil and freshly squeezed lemon juice over the top. Gently fold everything together until all pieces are evenly coated.

Allow the salad to rest at room temperature for 10 to 15 minutes before serving. This lets the salt extract the natural juices to form a rich, citrusy dressing at the bottom of the bowl.