Cut the pittas into triangles and brush with olive oil. Spread evenly on a baking tray, salt to taste, and bake until golden brown (about 10 to 14 minutes, depending on the thickness of the pitta).
Combine the sumac, lemon juice, extra virgin olive oil, salt, and pepper. Whisk, and set aside.
Spread out the chopped lettuce in the bottom of a large salad bowl. Top with the tomatoes, cucumbers, green pepper, mint, parsley, and spring onions. When you’re ready to serve, whisk the dressing, top the salad with the dressing and pitta chips, and toss everything together.