Prepare 8 dl (1⅖ pt or 3½ U.S. cups) Sauce Bordelaise taking care to use good quality red wine.
Pass 6 medium-sized raw duck livers through a fine sieve and add this purée to the hot sauce and mix well in. Heat the sauce very carefully so as to cook the liver but do not boil it, as this will have the effect of granulating the purée. Pass through a fine strainer and season well.
The characteristic of this sauce is a reduction of red wine with shallots with the addition of the purée of raw duck livers.
This sauce is the essential accompaniment for roast Rouen duck.