Step by step
Place the lemons in a pan of boiling water and cook for 20 minutes, drain, change the water, bring it back to the boil, replace the lemons and cook for another 20 minutes. Do the same for a third time.
Tips
To avoid making your lemon jam too thick, take care over the cooking times.
Trivia
The lemon tree is native to Asia and came to the Mediterranean only in the thirteenth century, thanks to the Arabs.