You would be surprised how easy it is to find red currant jelly in supermarkets. Every decent-sized one will carry it, and I've even found currant jelly in towns as small as Fayette, Missouri, and Ashley, North Dakota. If you really can't find it, though, use lingonberry or cranberry jelly. Raspberry is not as good a substitute. Oh, and if you can find syrup of any of these fruits, get that -- it dissolves easier in the sauce.
3tablespoonsunsalted butter,duck fat or cooking oil
1/4cupDemi-glace, or 1 cup regular stock
A pinch of salt
Zest of a lemon and an orange
1/4cupRed currant jelly
Freshly ground black pepper
Take the venison out of the fridge and salt it well. Let it rest at room temperature for 30 minutes.
Melt the butter in a saute pan large enough to hold the venison backstrap over medium-high heat. When it's hot, turn the heat down to medium and brown the venison on all sides. Use the finger test for doneness to cook the meat to the level you want. I prefer medium-rare. Remember it will continue to cook as it rests, so take it out a little before it reaches the doneness you want. Move the meat to a cutting board, tent loosely with foil and let it rest while you make the sauce.
When your meat has come out of the pan, make sure there is at least 1 tablespoon of butter or oil in it. If not, add more. Saute the shallot over medium-high heat for 90 seconds, just until it softens. Don't let it burn.
Add the Port wine and use a wooden spoon to scrape up any browned bits stuck to the pan. Let this boil furiously until it is reduced by half. Add the demi-glace (or stock), the salt, citrus zest, mustard and cayenne and let this boil for a minute or two. Stir in the red currant jelly and the black pepper. Let all this boil down until it is thick, but still pourable. You can strain it if you want a more refined sauce.
Slice the venison into medallions. Pour any juices that have come out of the meat into the sauce and stir to combine. Serve with the sauce either over the meat or alongside.
I make my own demi-glace (really glace de viande), but it takes some time to make. You can buy it at specialty markets (it's shelf stable), or you can buy it online. Cumberland sauce stores well for a couple days, and is surprisingly good cool or at room temperature; the English serve it cool with cold meats.