Put the wine, vinegar and shallots in a pan, add cayenne and sprigs of tarragon and chervil. Place the pan over a low heat and simmer the mixture for 15 mins or until only 3-4 tablespoons of the mixture remains. Strain the liquid into a bowl, then return to the pan. Reduce the heat to very low and whisk in the egg yolks.
After a few seconds, whisk in 1/3 of the butter and continue whisking until it is absorbed. Repeat this process twice more, whisking until the sauce begins to thicken. Remove the pan from the heat and continue whisking: the heat of the pan will continue to cook and thicken sauce. Stir in the chopped herbs and season the sauce with salt and pepper to taste.
