Place sugar and lemon juice in a saucepan. Bring to a boil, and reduce heat while stirring for about 5 minutes.
In a large mixing bowl, slowly stream hot mixture into egg yolks. Temper with a whisk.
Pour lemon curd back into saucepan, over medium heat, stir with a spoon (not a whisk ) until thickened. It takes about 5-10 minutes Remove from heat.
Incorporate 1 part at a time, (1/2 pound cold diced butter and 2 lemons zested on a fine grater) until all are mixed in.
Pour curd into a shallow long dish to cool in refrigerator for at least 1 hour.
Scoop curd into a serving dish for a teatime treat!Makes 4 Source: