Chop up fine two ounces of lean ham and a small piece of onion, add a
little celery, the stalks of parsley, one clove, one-half tablespoon
of pepper, and one-half bay-leaf. Pour over these ingredients a scant
one-half cup of vinegar. Cover the saucepan and allow it to boil until
it has consumed one-half. Put into another saucepan one-half cup of
bouillon (or water in which you have dissolved one tablespoon of
extract of beef). Allow it to boil, and then thicken with a teaspoon
of potato flour which has been diluted in a little cold water. Drop
this, little by little, into the saucepan until you have gained the
required thickness for the sauce. Then pour in the boiled vinegar,
passing it through cheese-cloth. Mix well together and add a teaspoon
of French mustard, some capers, and some chopped-up pickles. Serve hot
with meats or tongue. The pepper should predominate in this sauce.