Hollandaise

2 tablespoons white wine vinegar

1 tablespoon water

2 egg yolks

100g butter, at room temperature and cut up into 1cm cubes

Salt and pepper

Put the vinegar and water into a pan, and boil hard until reduced to about I tablespoon. Cool slightly.

Put the egg yolks in a basin, and stir in the reduced vinegar. Place the bowl over half a pan of hot water (NOT boiling) so the water doesn’t quite reach the bottom of the bowl. Heat gently, stirring all the time with a small whisk. As the egg yolks start to thicken, add a cube of butter and continue stirring while it melts. Repeat until all the butter is used up.

The resulting sauce should be almost thick enough to ‘peak’. Remove the bowl from the pan before the sauce gets too thick.

Serve the sauce warm, not hot, with asparagus.