First, make a roux by melting the butter in a saucepan over medium-low heat.
Add the flour and stir continuously using figure-eight motion to fully incorporate butter and flour.
After about 5-10 minutes the roux should change to a blond color. Slowly add broth and pan drippings to roux. Whisk constanting until gravy is lump free and reaches desired thickness.
For additional flavor add a small amount of a rich, high quality red wine.
Taste and add salt and pepper if needed.
**If tenderloin doesn’t render enough pan drippings, make gravy as above. Once you slice the tenderloin it will release a lot more juice that can be added to existing gravy for added flavor.