This recipe is very simple: lemon juice and zest, eggs, sugar, and butter.
1/2 cup fresh squeezed lemon juice
1/3 cup granulated sugar
1 egg yolk
2 tsp. lemon zest
pinch of salt
1 stick of butter, cut in half
Whisk together lemon juice, sugar, lemon zest, eggs, egg yolk, and salt together over a double boiler over medium-high heat.
Whisk continuously for 7-10 minutes until the mixture starts to thicken and begins to smell distinctly like lemon curd.
Turn off heat and add butter, folding in with a spatula. Mix butter into curd until the butter is completely melted and incorporated.
Place fine mesh strainer over a bowl. Pour curd into strainer, and lightly push it through with a spatula. This will make sure your curd is smooth and strain out any small pieces of egg or seeds.
Place into a airtight container and store in refrigerator for up to 4 days.
Curd will thicken further after a few hours in the refrigerator.