Packaged Brown Gravy Tip - You Won't Believe This

I was at a friends house and she had served roast beef and gravy.  The gravy was unbelievable, I could have just drank the gravy it was so good.  I asked her how she made her gravy and she laughed at me.  She showed me that it was a brown gravy mix with a secret ingredient.  "What could this secret ingredient be?" I thought to myself, I need to know.  After a little prodding, I wriggled it out of her.  Balsamic vinegar.  Huh?  How could that be?  I didn't believe her, I thought that she was pulling my leg.  So the next time I made a package of brown gravy, I tried a little balsamic vinegar and low and behold, she was right.  I had to experiment with it a little and found the formula to be this:

1 package of brown gravy mix (prepared as directed) + 1 teaspoon balsamic vinegar.

Sounds odd, but nobody will believe you that you are serving them brown gravy mix from a package.  Or, they will want your recipe.  It will be up to you if you want to dilvulge the secret.  It could be just between you and me.