The classic dressing for asparagus
• 2tbsp tarragon vinegar
• 1 sprig of tarragon (optional)
• 2tbsp water
• 2 large egg yolks
• 225g soft unsalted butter
1) Put the vinegar, sprig of tarragon (if using) and water in a small pan.
2) Boil rapidly to reduce it by half.
3) Remove the tarragon.
4) Tip the mixture into a heatproof bowl, add the egg yolks and whisk. (One of those cute little spiral hand whisks comes in handy here.)
5) Stand the bowl over a pan of simmering water and whisk for a few minutes more until the mix has increased in volume and looks lighter.
6) Gradually add the butter a small piece at a time, whisking continuously. Don’t add another piece until the first piece has been fully incorporated. Keep going until you’ve added all the butter and the mixture has the consistency of mayonnaise.
7) Serve warm, drizzled over spears.