Finely mince two ounces of onions and brown them slightly in two ounces of butter. Moisten with one-quarter pint of white wine and the same quantity of vinegar; almost entirely reduce the liquid; add one and one-half pints of clear half-glaze, and set to cook slowly for half-an-hour. Rub the sauce through a sieve.

The onion may be left in the sauce or not, according to taste.