Unsalted butter (Make sure it's unsalted otherwise the curd will not thicken)
Grate the lemon peel, squeeze out the juice, and strain. Thoroughly whisk the egg, and be sure to strain.
Put all the ingredients into a sauce pan, and heat over hot water. The hot water should be about 80℃.
Stir continuously with a wooden spatula. It will start to thicken, so continue mixing. When it gets to the desired consistency, it's done!
It will harden once it cools, so remove it from heat while it is slightly thin. Transfer to a sterilized jar to store.
For a recipe that uses this lemon curd, try "Lemon Curd and Cream Cheese Tart" (Recipe ID: 880924).
Story Behind this Recipe
I wanted to make an authentic tart, sweet, and tasty lemon curd.
Be sure to strain the egg. Otherwise the egg whites will harden and form lumps. If the temperature of the hot water bath is too high, the egg will harden, and if it's too low, the curd will not thicken. Please adjust the temperature while mixing. It should keep for about 1 week in the refrigerator.