Shake the elderberry blossoms to remove any foreign matter and insects. Remove large twigs and large stems, then rinse in a bowl of water. Gently shake off the water and spread them evenly on a towel or kitchen paper.
Pour water into a saucepan and bring it to a boil, add sugar and cook for a few minutes, stirring occasionally, until the sugar is completely dissolved.
Remove from heat, add elderflower flowers and lemons, washed and cut into wedges.
Cover and leave to infuse for 2 days in a cool place. The need for cold is due to the fact that at room temperature, the mass can ferment.
After 2 days, filter the liquid through cheesecloth or a fine strainer, add citric acid, put on fire and bring to a boil. Cook for 2 minutes, stirring occasionally.
Pour the hot syrup into sterilized bottles, seal and let cool.
When the bottles are cool, store in a cool and dark place. From the moment the bottle is opened, the syrup must be stored in the refrigerator.