Wash and dry lemons. Juice lemons. Strain the juice for smoothest lemon curd. Set juice aside.
Fill the bottom pot of your double boiler with 1-2 inches of water. Place on high heat. Once the water begins to boil, reduce to low heat to keep the water at a simmer.
Place granulated sugar, egg yolks, lemon juice and pinch of salt into the top pot of your double boiler.
Wisk until completely blended, then continue to whisk as the curd cooks.
Whisk and cook for about 10 min or until the mixture becomes thick. It should coat the back of a wooden spoon and leave a clear pass if you run your fingers through it. If you have thermometer, it should register 75oC/170oF.
Cut room temperature unsalted butter into small pieces
Remove pan with curd from heat. Strain to clean glass bowl to remove any lumps that may have formed.
Add pieces of butter and mix with the wooden spoon.
Transfer the curd into glass jar and cover with plastic wrap “to contact” (place plastic wrap directly on top of the curd). Allow the lemon curd to cool slightly, then place into refrigerator.