This can be prepared a little ahead – it will hold for about 30 minutes.
- Preparation time: 10 minutes
- Cooking time: 10 minutes
- Total time: 20 minutes
½ shallot (about 20g), finely diced
60ml dry white wine
40ml white wine vinegar
2 egg yolks
150g unsalted butter, melted and kept warm
2 tsp fresh tarragon, finely chopped (about 4-5 sprigs)
1. Put the shallot, wine and vinegar in a saucepan. Bring to the boil and cook until reduced by half. Transfer to a heatproof bowl and set over a pan of barely simmering water (the bowl’s base should not touch the water). Add the egg yolks and a pinch of salt; whisk until it doubles in volume (about 3-4 minutes) and holds a figure of 8 shape.
2. Take off the heat and gradually whisk in the butter, a little at a time. Stir in the tarragon before serving.