Start by first sorting out the violets from the twigs or other unwanted items. Remove the stems of the flowers.
Put a very fine strainer (such as a chinois) over a saucepan.
Rinse the violets under a thin stream of cold water.
Put the flowers in a bowl and pour over the water and lemon juice.
Cover the bowl, put it in a cool place and let infuse for 24 hours.
The next day, put a very fine strainer (such as a chinois) over a saucepan and pour the content of the bowl.
Squeeze the flowers well with the back of a spoon to extract the maximum of juice and color your syrup for several minutes.
Add the sugar and cook on a very low heat for 8 minutes.
Meanwhile, sterilize a jar or a small glass vial with boiling water by boiling your container for 10 minutes. Then put them upside down on a clean cloth.
Once the syrup is ready, pour it immediately into the sterilized jar and close.
Store in a cool place and consume within a few weeks.