- 4 tablespoons lemon juice
- 4 large egg yolks
- 225 g unsalted butter, softened
- a little salt and freshly ground black pepper
Put a heatproof bowl over the saucepan so that it rests on the rim. Put sufficient water in the saucepan so it is just under, but not touching, the bottom of the bowl. Bring this water to a simmer and maintain at a simmer, not a rapid boil.
Put the lemon juice, 2 teaspoons of water, and seasoning into the bowl. Beat in the egg yolks and a small piece of the butter, beating lightly until the consistency thickens.
Add the remaining butter, a little at a time, beating the sauce well between additions. When all the butter has been incorporated the sauce should be thick and glossy. Taste and adjust the seasoning before serving. To keep the sauce warm for no more than 15 to 20 minutes, remove the pan with the bowl from the heat and cover the sauce with a piece of wet, crumpled baking parchment.
If the sauce begins to curdle, it is probably due to the heat being too high, or the butter being added too quickly. Remove from the heat and beat well before proceeding.
If the sauce does separate on standing, beat in a tablespoon of cold water before serving.