Pick the flowers when they’ve opened i.e still with lots of pollen. Flowers that have not opened or have passed over do not give good flavour.
Cut 30 heads of elderflowers into a large sterilised bowl or bucket, add 2 sliced lemons (non waxed ones) and 1.5 kg of Sugar, mixed with 50g citric acid (you can buy this from the chemist). Pour on 1.5 litre of boiling water and leave for 5 days to mature, stirring everyday.
Serve mixed with sparkling water, slices of lemon and ice – delicious