No. 26 Sauce Piquant
Put a large spoonful of sweet butter in a stewpan, slice into it two onions, two carrots, a little thyme, two cloves, two eschalots and a bunch of parsley; add, if liked, a clove of garlic. Let them cook until the carrot is soft, then shake in a little flour; let it cook five minutes more, and add a cup of beef or veal stock, and half a cup of strong vinegar; skim and strain through a sieve. Add salt and pepper when boiling. This is nice on cold meat.