Chop the tomatoes, onion, peppers, chillies (if using) and parsley by hand, then put them into a large bowl. Add the sumac, pomegranate molasses, vinegar, olive oil, sea salt and black pepper to taste before giving everything a stir.
Cover with clingfilm and put it in the refrigerator for 15 minutes to allow the dressing to macerate the vegetables.
Once ready to serve, arrange on a flat plate and flatten with a fork, drizzle with a little extra virgin olive oil and sprinkle with a couple of pinches of sumac.