Step 1

Set a strainer over a bowl and keep it readily available near the stove.

Step 2

In a heavy non-reactive saucepan, beat the egg yolks, sugar, and butter until well blended (beating the egg yolks into the butter and sugar will help prevent the eggs from curdling and clumping).

Step 3

Stir in the lemon juice, zest, and salt. Cook over medium-low heat, stirring constantly, for about 10 to 12 minutes until thickened and has a glossy appearance. Try not to let the mixture come to a boil, if it begins to boil remove it from the heat for a bit, then return it to a lower heat. The curd should cling to a spoon or spatula and leave a trail if you run your finger through it.

Step 4

Pour it into the strainer and press it with the back of a spoon. Discard the lemon zest and any lumps that are left behind in the strainer.

Step 5

Place in the refrigerator to chill. The lemon curd will thicken more once it has chilled completely.