Preheat oven to 350°F/175°C. Cut pita into small squares Mix together the evoo, sumac and salt. Place pita squares on a baking sheet and brush with the sumac mixture. Bake for 20 minutes. In a large serving bowl combine lettuce, radishes, tomatoes, cucumber, pepper, onion, mint, parsley, and watercress. Add pita chips to salad.  In a small bowl, mix lemon juice, evoo, sumac, salt, and pepper. Pour over salad and toss before serving.