Put the egg yolks, a knob of butter in pieces, a pinch of salt and half a tablespoon of water in a saucepan.

Place the saucepan in a bain-marie over hot water, but not boiling.

Dissolve the egg yolks with a whisk and as soon as the pieces of butter start to melt, gradually incorporate the rest of the butter while continuing to beat with the whisk.

When the sauce is well whipped and fluffy, complete it with a couple of spoonfuls of lemon juice or white wine vinegar that you will gradually add while stirring.

Ideal for boiled fish, asparagus, Brussels sprouts and other boiled vegetables.

Note that hollandaise sauce, one of the fundamentals of international cuisine, is not difficult to make but requires a lot of attention: the heat must be moderate, the butter must be completely absorbed before adding more, the sauce must be beaten with the whisk and not stirred as is done for mayonnaise and must be heated exclusively by hand.