Beat together the lemon juice, sugar, eggs, egg yolks and lemon zest in a glass bowl. Place the bowl over a pot of simmering water, without touching the water, and whisk continuously until the mixture thickens, about 20 minutes. Remove from the heat and whisk in the butter. Let cool and refrigerate for best taste.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.