Sometimes having some not-so-fresh ingredients around can lead to some good discoveries. Some slightly mushy grapes led to this sauce which I used as a marinade and sauce for some grilled sirloin steaks.
Fill a 2 cup liquid measuring cup to the top with halved grapes. Fill in the empty space with some whiskey or bourbon, right up to the 2-cup line. You can substitute something like apple juice or good quality vinegar if you want. Set these aside and let them soak while you chop some other vegetables.
Place a couple tablespoons of olive oil in a nice and wide stockpot, the kind you would use for gravy. Set it over medium heat. Chop up 1 large onion and 3 or 4 cloves of garlic. Put these in the olive oil and let them sweat.
Next chop up 2 large, or 3 or 4 smaller, tomatoes. Add these to the onions and garlic along with the grapes and whisky. Season with some salt and pepper. Bring to a boil, stirring constantly. Reduce to a simmer and add in a few sprigs of thyme or other fresh herbs.
Allow this to simmer until the liquid has reduced by at least half, maybe more like two-thirds for a thicker sauce. When you pull your spoon through the sauce it should take a few seconds for the liquid to fill back in.
Puree the sauce using a stick blender, blender, or food processor. You can continue to simmer and reduce it if it still seems too thin.