Wash the elderflowers and organic lemons. Carefully peel the lemons and squeeze out the juice. Place the juice, peels, vinegar and elderflowers in a large pot and add water. Let sit in the shade for 3–4 days, stirring occasionally. Strain the elderflowers and bring the liquid to a boil. Stir in the sugar well. Then pour into bottles, seal tightly and store in a cool, dark place.
The syrup should be diluted with water before drinking.