Iranians love all things sour: lemons, limes, pomegranate molasses, young plums and tamarind. I especially love tamarind because you can use it so well in savoury cooking and balance it with sweetness to create something really delicious. In this recipe, I simply mix tamarind paste with honey to make a marinade that has lots of flavour without much effort. These prawns are also great to skewer and are easy to cook on the barbecue.