Directions
Prepare your double boiler. Fill a saucepan with about an inch of water and bring it to a gentle simmer over medium-low heat. The water should be steaming, not boiling.
Whisk the yolks.
In a heatproof glass or stainless steel bowl, whisk the egg yolks and fresh lemon juice together until they are pale, frothy, and slightly thickened.
Gently cook the base.
Place the bowl over the simmering water, ensuring the bottom of the bowl does not touch the water.
Whisk constantly until the mixture doubles in volume and is thick enough to leave a ribbon trail when you lift the whisk. This is the most crucial step for a stable sauce.
Emulsify the sauce.
Remove the bowl from the heat.
While whisking vigorously, begin adding the warm melted butter, literally one drop at a time.
Once you see the sauce begin to thicken and emulsify, you can slowly pour the rest of the butter in a thin, steady stream, whisking constantly until it's all incorporated and the sauce is smooth and glossy.
Season and serve.
Whisk in a pinch of salt and cayenne pepper or hot sauce, if using.
Taste and add more lemon juice or seasoning as needed. For the best texture and flavor, serve immediately over poached eggs, asparagus, or fish.
Keep the heat gentle. If the eggs get too hot, they will scramble. If the bowl feels too hot to the touch, briefly lift it off the heat while continuing to whisk to control the temperature.
