There are a lot of times, when I don't have the time, or the inclination to make a gravy from scratch with a roux and all. Most of the time it's because I'm eating leftover meatloaf, hamburgers, london broil, etc. These things heat up easy when dipped in a gravy, that can also be used on mashed potatoes, rice, or noodles.
I made this one, on a day when I did Filet Mignon out on the grill. We wanted to have nice creamy mashed potatoes and gravy with it, so I had to punt, and make it from canned. I did it well ahead of cooking the steak, so all I had to do was to re-heat it while the steak was resting.
1. Slice the onion, and cook over medium heat, in a little vegetable oil until real soft. Add the garlic, and cook for another 4 minutes or so.
2. Turn the heat up to high, add the balsamic vinegar, and reduce until it's almost a syrup. Add the brandy flame it, to burn off most of the alcohol, and let this reduce to a syrup.
3. Add the beef broth and blacken, turn the pot down to a slow boil, and cook without a lid until the liquid is reduced to about 3/4 of it's original volume.
4. Make a slurry, by mixing 2 tablespoons of cornstarch with about 1/4 cup of water. Turn the pot back to high heat, and add 1/2 of the slurry with one hand, while you're stirring it with your other. AT this point you're trying to get the slurry mixed in without turning to lumps. Let the gravy come back to a boil, and check for thickness, and add a little more of the slurry if you need to. The cornstarch won't thicken unless the mixture has come to a boil. When you've got the gravy (sauce) to the right consistency, you should check for salt, and serve.
5. This can be made well in advance of you meal and re-heated just prior to serving.
6. You could make a variation of this by replacing the balsamic vinegar and brandy with a good red wine, or an inexpensive ruby port.
You could let the gravy reduce to 1/2 of it's original volume, then add a little heavy whipping cream, or sour cream (the sour cream would turn it into a stroganoff type gravy). Just go ahead and change the flavors to compliment whatever you'll be serving this with.