Put the pearl barley in a small saucepan and boil for 30-35 minutes until tender.
Meanwhile, chop the tops off your tomatoes and squeeze out the seeds, then dice, along with your orange pepper. Slice the spring onions into 1 cm rounds, and put all the veg in a large salad bowl. Chop all of your herbs with a very sharp knife to avoid bruising them (minding fingers...) and add to the same bowl.
Drain the pearl barley in a sieve, rinse with a good wash of cold water and add to the bowl. Dress with lemon juice and olive oil, and season with sumac and black pepper.
Recipe by Veggie Runners at https://www.veggierunners.com/2013/09/15/marathon-carb-loading-pearl-barley-tabbouleh/