Set up your ingredients ahead of time
Once you get started making the sauce, it's difficult to change gears. Arrange the following:
- Put a pot of water on to make a double boiler.
- 3 to 4 eggs (some say room temp is best)
- 1 1/2 to 2 tablespoons lemon juice (for flavoring the sauce)
- About 9 fluid ounces (a little over a stick) melted clarified or regular butter (there is an ongoing debate about which is better...try whatever you have on hand)
- 1 1/2 fluid ounces room temp water
- Cayenne pepper (classic, but optional)
Separate the yolks
of three to four eggs into a stainless steel bowl. If you pride yourself on thriftiness, you can freeze the whites for another use.
Whisk the yolks
until smooth, then add the water and continue whisking for about a minute. The mixture should fluff up to near double its original volume.
Set up a double boiler
by placing your egg bowl over the pot of simmering water. The water should not touch the bowl. (Braver souls can just start and finish the process in a saucepan and place it over medium-low, direct heat.) Whisk constantly and rapidly until the mixture begins to thicken.
Continue whisking until very thick
almost the consistency of whipped cream. This may take about 4 or 5 minutes depending on how high your heat is. (At this stage, the mixture is also called a Sabayon.)
Remove the bowl from the heat
and place it on a countertop with a damp dishtowel beneath it for stabilization while you whisk.
Begin adding the melted butter (be sure its no longer very hot), starting with a very small amount and whisking constantly. This is the most important step. If the first addition of fat does not properly absorb into the yolks, your sauce will be grainy and greasy, and never emulsify.
Continue to trickle in the butter while you whisk.
Once the sauce has reached the thickness you like, you can technically stop adding the butter. Any additional butter added here would mainly serve to stretch the quantity of the sauce.
Finish with the lemon juice, salt, and a teeny pinch of cayenne to taste. Or add your own touches like pureed vegetables, minced parsley, chives or tarragon, chopped cooked mushrooms, orange zest, or whipped cream.