Pick the mint and wash well.
Place in a wide bowl with the sliced lemons.
Bring water to a boil, stir in sugar, boil again and then pour over mint leaves.
After an hour, stir in the citric acid.
Allow mint syrup to steep for about 3 days, lightly covered, then pour into sterile glass bottles and store in a cool place.
Preparation Tip:
Mint syrup tastes good sprayed with mineral water or with sparkling wine or white wine.