Hollandaise takes patience. You need to slowly warm — or temper — the eggs before introducing them to your recipe so they don’t curdle.
The Steak Issue
4 egg yolks
1 tablespoon freshly squeezed lemon juice
½ cup (1 stick) unsalted butter, melted
Vigorously whisk the egg yolks and lemon juice together in a stainless-steel bowl until the mixture is thickened and doubled in volume. Place the bowl over a saucepan containing barely simmering water (or use a double boiler). Continue to whisk, being careful not to let the eggs get too hot or they will curdle (separate). Slowly drizzle in the melted butter and continue to whisk until the butter is emulsified and the sauce is thickened. Remove from heat, and 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.