Old-Fashioned Ravigote Sauce

This sauce has a peculiar history and, while it is always based on herbs, it has been made in several ways. Since the eighteenth century it has been served hot and made by adding various assorted herbs, chopped or crushed in a mortar, to a velouté sauce (basically broth thickened with flour). But throughout this time there have been cold versions, essentially vinaigrettes. These cold versions make delicious accompaniments to meaty foods, but their herbal freshness makes them especially deli