For the lemon curd, wash 4 large lemons, if possible untreated, and first grate the peel.
Then squeeze out the juice and bring to the boil together with the zest, sugar and 1 heaped tablespoon cornstarch in a saucepan, stirring constantly.
Add crushed butter and melt. Now reduce the temperature and continue stirring over medium heat with a whisk.
Beat eggs , pass through a fine sieve and add as well. It must not boil now, otherwise the egg will flocculate. Continue stirring until a thick mass is formed. It takes about 15-20 minutes.
Immediately pour into hot rinsed jam jars. Makes about 2 jars. The lemon curd can be stored in the refrigerator for about 2 months.