Throw lemons into a pot of boiling water for 1 minute. Remove and dry thoroughly with a hard towel.
Thinly cut the zest from the lemons (without the white part) and pour 1 liter of boiling water over it. Pour sugar; insist 4 hours
Squeeze the juice from the lemons along with the pulp, add to the infusion. Leave for another 6-8 hours in the refrigerator. Strain and serve.