In a saucepan, grate the zest of four lemons and squeeze out the juice, about 85 ml.
Add the sugar, 4 egg yolks and a pinch of salt to the saucepan. Whisk with a whisk until smooth.
Place a saucepan over medium heat, heat for 1-2 minutes, stirring constantly with a whisk. Add 100 g of butter.
Cook over medium-low heat, stirring constantly, until the mixture thickens, about 7-8 minutes. Do not bring to a boil.
Strain the kurd through a fine sieve.Store the kurd in a jar with a tight fitting lid. Lemon curd can be stored in the refrigerator for up to 2 weeks.
