The sugar content has been kept low so that the subtle flavours shine through. The result is a truly refreshing, delicately scented delight. Keep it in the freezer to enjoy in the garden on a warm spring or early summer afternoon, or serve it during a dinner party as a palate-cleansing amuse bouche between the main and dessert courses.
750g forced rhubarb, cut into 5cm chunks
600 ml water
150g caster sugar
4 lemongrass stalks