Step 1

In a small saucepan, add egg yolks, sugar, lemon juice, lemon zest, and salt. Whisk until completely combined.

Step 2

Cook over medium-low heat, whisking constantly until mixture thickens and bubbles, about 10 minutes.

Step 3

Remove from heat and add the butter. Continue to whisk until fully combined and smooth.

Step 4

Pass the lemon curd through a fine mesh strainer to remove the zest for a smoother curd (optional).

Step 5

Transfer to a glass jar and let it cool to room temperature, about 1 hour. Cover and store in the refrigerator for up to 2 weeks.