This is the simplest and most magical of the kitchen sauces. There is no real reason why it should work, but it does work extremely well. Be painstaking and do not try rushing.
In a heavy stainless-steel or enameled saucepan, boil the wine and vinegar with the shallots and a pinch of salt until only enough liquid remains to moisten the shallots. Remove the pan from the heat and allow to cool for a few minutes.
Season with pepper. Place the pan on a fireproof mat or flame diffuser over a very low heat. Whisk in the butter, a handful of dice at a time, until the sauce has a creamy consistency. Remove from the heat as soon as all the butter has been incorporated. You may find that you need a little more or a little less butter.
© 1999 Jennifer Paterson and Clarissa Dickson Wright estate. All rights reserved.