My new favourite sauce

I recently got an ebook version of The London Art of Cookery by John Farley, first published in 1783, which is available free on Google Books or at Archive.org.  There are some good-looking recipes in this book and I'm excited to try them.  So when I braised some beef on the weekend and didn't want to waste the braising liquid, I made French Olive Sauce from page 149.  This is a very simple sauce recipe.  All you need to do is simmer olives in stock, and season with salt, cayenne pepper and lemon.

Although this is an 18th century recipe, it has what I think of as a very modern taste: strong and salty with rich umami overtones.  It goes well with beef and vegetables, and I strongly recommend it.

Like many recipes from this time period there are no ingredient quantities listed.  This is because you don't need exact quantities.  If you did, Farley would tell you, as he does with many of his other recipes.  With this one the quantities involved depend on how much sauce you want and how much of the ingredients you have available.  I used about a cup of stock and maybe half a cup of finely chopped olives.

The recipe doesn't specify whether to chop the olives, but I recommend chopping them finely so they'll mix through the sauce.  The recipe doesn't specify how long to stew the sauce either, but mine simmered on a medium low heat for about an hour.  Depending on your stock, you may not need to add any salt, so be sure to taste the sauce before you season it.  If it doesn't thicken up as much as you'd like, a sprinkle of cornflour will solve that problem.  The recipe specifies veal stock, but I used beef stock and you could probably use any kind of stock, including vegetable stock if you wanted to make a vegan version.