1 tablespoons lemon zest
4 ounces lemon juice
4 ounces butter, softened
1 cups granulated sugar
Combine the zest, lemon juice, butter, and sugar in the top of a double boiler and heat, slowly, until the butter is melted and the sugar is dissolved. Stir occasionally.
Whisk the eggs until blended well.
Temper the hot juice mixture into the eggs and return the curd to the double boiler. Heat slowly and stir almost constantly until the mixture is thick. (about 20 minutes)
Remove from the heat and cool for service.