Directions
Preparation:10min  ›  Cook:5min  ›  Extra time:4hours  ›  Ready in:4hours15min 

1. Rinse the pearl barley in a sieve under cold, running water and drain well. Tip the rinsed barley into a saucepan, cover with cold water and bring to the boil, then reduce the heat and cook gently for 5 minutes. Pour the barley back into the sieve and rinse again.
2. Put the cooked barley into a large jug or bowl. Rub each sugar cube over the skins of the lemons to extract the oils, then add the cubes to the jug or bowl.
3. Pour in the boiling water and stir until the sugar has dissolved. Cover the jug or bowl with a clean tea towel and leave to infuse for 3 hours, or until cold.
4. Squeeze the juice from both lemons and add it to the barley water. Strain through a nylon sieve into a serving jug. Cover and chill for 1 hour. Put several ice cubes and one or two lemon slices in each of four tall glasses, pour in the lemon barley water and serve.