What red wine reduction means
A red wine reduction is a sauce or flavour base made by boiling red wine until much of its water and alcohol have evaporated, leaving a concentrated, glossy, syrupy liquid. The wine is usually simmered in a wide pan with finely chopped shallots and sometimes garlic, thyme, bay, peppercorns or a little sugar, which adds sweetness and helps the reduction become glossy. It is reduced until a large part has evaporated and it coats the back of a spoon. For a richer sauce, beef, veal or chicken stock is added and reduced again.
The reduction is strained to remove the shallots and herbs, then often finished by whisking in cold butter, a technique called mounting, which gives a velvety texture and shine. Red wine reductions are used as sauces for steak, beef fillet, lamb, duck, venison and even meaty fish such as salmon, and they are the basis of classic French sauces such as bordelaise and marchand de vin. Sweeter versions, sometimes with port, sugar or berries, are served with desserts, cheese or poached pears. Using a good, fruity, not overly tannic wine is important, as any harshness is concentrated by reducing.
A wide pan speeds up evaporation. Care is needed near the end, as the syrupy liquid can burn. You will see red wine reductions on restaurant menus and in sauce recipes.