1 egg yolk
75g butter, melted
splash cold water
squeeze of lemon juice
- In a glass bowl, whisk the egg yolk with a splash of cold water until thickened.
- Place the bowl over a pan of barely simmering water.
- Add the melted butter in a thin stream whisking all the time until the sauce has the consistency of mayonnaise.
- Serve immediately and add a squeeze of lemon.