There is an old adage that if a wine is not fit to drink, then it isn’t fit to cook with. That doesn’t, of course, mean that you should pour your Rioja Reserva in the stockpot, but nor should you throw in some old vinegar. If you get through it quickly enough, you can keep some cheapish wine in stock for that purpose, but if not, then perhaps buy a mediocre wine and, well, you’ll just have to drink the rest.