Tarragon Butter Sauce

Melt the butter and skim off the foam. Set aside to cool off.

Put the shallots, wine and vinegar in a small saucepan. Reduce by half over medium heat (about 10 minutes). Allow to cool completely. Strain through a sieve and set aside. 

Over a double boiler heat egg yolks.

Beat until creamy (don't allow it to get too hot - you don't want to scramble the eggs), remove from the heat and add the butter, drop by drop to start with, and then in a thin stream, stirring constantly, until the sauce is creamy and shiny.

Stir in the tarragon and chervil, and whisk in the reserved wine/vinegar liquid.