Steady. Steady. You can get through this, Joe. Then you can run back to the kitchen, dive headfirst into this golden bowl of goodness, and never come up for air. OK. Start by combining the eggs and sugar in a small, heavy — non aluminum — sauce pan.
Whisk until they’re combined.
And the juice, salt, and soft butter…
…and whisk until combined. Put the pan over medium-low heat, and while whisking constantly, heat the mixture to 196 F…
…or until it does this on the back of a spoon:
Whisk in the zest:
Stores 3 weeks in the fridge. And now if you’ll excuse me…
This is a pretty easy thing. What you want to guard against — just as with all custards — is overcooking it, which will cause the egg proteins to clump up and fall to the bottom. You want to bring the mixture to a target of 196 degrees F, a degree or two more is no biggie, just don’t get it to boiling temperature. But truth be told even that isn’t a disaster…there are more than a few pastry pros out there who let their curd boil (the “curds” can be strained out and hey — at least you know your eggs are cooked completely!). I don’t recommend it. Use a thermometer. The formula is:
4 egg yolks
5 ounces sugar
3.25 ounces (by weight) lemon juice
2 ounces softened butter
2 teaspoons lemon zest
Whisk the yolks and sugar together until combined in a heavy saucepan (NOT aluminum…ever seen green eggs? You will.). Add the remaining ingredients — save for the zest — to the pan. Over medium-low heat, and while whisking constantly, bring the mixture to 196 degrees, until it coats the back of a spoon. Promptly strain the mixture through a fine sieve. Stir in the zest and allow to cool.