Dissolve sugar in water over a gentle heat, then bring to a simmer.
Pour over the
elderflower heads with the zest from the lemons –
use a potato peeler to get nice wide strips. Slice
the rest of the lemons and add to the syrup with citric acid.
Stir well, cover and leave for 24 hours in a cool
place to infuse. Strain through muslin and pour
into sterilised bottles. Once open, refrigerate.