Step 1

Whisk together lemon juice, lemon zest, sugar, and eggs in a large heavy bottomed saucepan over medium low heat, stirring as needed. Bring to a slow simmer and immediately add butter, whisking constantly until curd is thickened and will stick to the back of a spoon, about 10 minutes.

Step 2

Strain curd through a small mesh strainer into a medium bowl with a lid, or cover tightly with saran wrap. Chill for at least an hour, or until cold. If you don't eat it all in a week (which I have no idea how you wouldn't), toss it out after 7 days.