The following is the resumption of my periodic reprints of entries from the classic cookbook/bible, Larousse Gastronomique. Billed on the front cover as “The World’s Greatest Culinary Encyclopedia,” the book is 1,350 pages long and contains 3,500 recipes. First published in 1938, the LG is an indispensable reference for anyone who fancies them self to be a serious cook. It’s also a great read for people who like to eat and like to kick around in the kitchen on the weekend. While it does have a cover price of $75 (and is well worth it), you can often find it for 30% off at Barnes & Noble (see link @ end of entry).
Larousse Gastronomique p. 385
Cumberland Sauce
A traditional English sweet-sour sauce that is usually served cold with venison, braised ham, mutton, or roast or braised duckling. It is made with port, orange and lemon juice and zest, and redcurrant jelly.
RECIPE
Cumberland Sauce
Remove the zest from an orange and a lemon and cut into fine strips; cook 1 generous tablespoon of the zest very gently in 200 ml (7 fl. oz, 3/4 cup) port for about 20 minutes. Remove the zest and add to the port 2 tablespoons redcurrant jelly, then a pinch of cayenne. Mix, bring to the boil, add the juice of the orange and lemon, then strain. Mix in the cooked strips of zest.

Larousse Gastronomique: The World’s Greatest Culinary Encyclopedia
French-language edition:
Larousse Gastronomique (French Language Edition)