Vigorously whisk the egg yolks and lemon juice together in a stainless steel bowl until the mixture is pale yellow, thickened and doubled in volume.
Place the bowl over a saucepan with barely simmering water; the water must not touch the bottom of the bowl.
Continue to whisk rapidly. Be careful not to let the eggs get too hot or they will scramble.
Slowly drizzle in the melted butter and continue to whisk until the sauce is thickened and doubled in volume. Remove from heat, whisk in cayenne and salt.
Cover and place in a warm spot until ready to use. If the sauce gets too thick, whisk in a few drops of warm water before serving.
Notes
Troubleshooting:
A tell-tale sign of a broken hollandaise sauce is if it’s grainy in texture, the butter is pooled on top, or it’s thin in consistency. Broken sauces happen typically because the emulsion never formed in the first place, due to various causes.
Adding in the butter in too quickly
The egg yolk heated up too much and the emulsifying properties are lost
The yolks are overcooked and the sauce is curdled and grainy
The butter is too hot when it was added in
Variations:
Noisette Melt the butter over medium-low heat and continue to cook until it has a nutty fragrance and the milk solids have fallen to the bottom and turned golden, about 7 minutes. Skim the surface but use the golden milk solids from the bottom. Continue with the hollandaise recipe. The subtle nutty notes of the brown-butter pair beautifully with sole or flounder.
Béarnaise Simmer 1/4 cup white wine vinegar and 2 Tbs. dry white wine with 2 Tbs. minced shallot and 2 sprigs of fresh tarragon until reduced to 1 Tbs. of liquid. Remove the tarragon sprigs. Continue with the hollandaise recipe, using the vinegar reduction instead of the lemon juice. Finish with 2Tbs. chopped fresh tarragon instead of the lemon zest. This is a classic served with a pan-seared filet mignon.