Melt and then cool the butter. Boil the vinegar, wine, peppercorns, shallots and tarragon until reduced to 1 tablespoon. Add 1 tablespoon of water to cool the mixture. Add the egg yolks and seasoning, whisk over low heat until light, about 4 minutes. Off the heat, whisk in the tepid butter until the sauce thickens. Strain the sauce and stir in the parsley. Serve warm.
HOLLANDAISE SAUCE:
In the top of a double boiler whisk together the egg yolks, vinegar, salt and pepper. Place the bowl over simmering water and whisk in the butter, a little at a time, whisking constantly until the sauce has the consistency of mayonnaise. Whisk in the lemon juice and season to taste.
