Put the pearl barley and 1 litre/1¾ pint water in a pan together with 1 teaspoon of salt and 1 tablespoon of the olive oil. Bring to the boil, then turn down to a simmer and cook for about 25-30 minutes or until just tender (it should still have some bite). Drain and allow to cool.When cool, mix together the pearl barley with the spring onions, pomegranate seeds and herbs. Season with salt and pepper.Whisk together the remaining 4 tablespoons of olive oil and the pomegranate molasses with a pinch of salt, and dress the salad with it, mixing gently. Taste to check the seasoning and adjust as needed.Serve topped with the pistachios.