Directions
Add the butter or drippings to a skillet and melt over medium-high heat. Add the onions and garlic and cook for 3-4 minutes.
Whisk in the flour until it is incorporated and simmer for 1 minute.
Add the red wine and whisk constantly to prevent lumps.
Simmer for about 2 minutes (the mixture will thicken).
Whisk in the beef broth and let it simmer for another 2-3 minutes until slightly thickened.
Add the remaining ingredients, return the mixture to a boil, reduce the heat to a slow simmer, and simmer uncovered for another 15 minutes. The liquid will reduce.
Add salt and pepper to taste.
Pour the mixture through a fine mesh strainer.
Serve the au jus immediately or refrigerate until ready to serve (reheat in microwave).