Put the barley in a saucepan of boiling water and cook for about 1 hour until the grain cracks. Strain and allow to cool. Preheat the oven to 85°C (185°F). Spread the barley on baking trays and dry in the oven for 2 hours. Heat the oil in a saucepan to 185°C (365°F) and deep-fry the barley in batches until it is puffed and golden. Remove from the oil and drain on kitchen paper.
In an airtight container in a dry place for up to 6 days.