Jägersauce

Melt the butter/lard/tallow in a stainless steel pan over medium-high heat and fry the onions until beginning to brown.  Add the garlic and cook another minute.

Add the mushrooms and cook 7-8 minutes or until golden and the liquid from the mushrooms has evaporated.

Add the butter and melt.  Add the flour, stir to combine and cook for about 3 minutes, stirring continually. This will cook off the flour flavor and brown the flour to create more depth of flavor in the gravy.

Deglaze the pan with the wine, scraping the fond for maximum flavor.

Add the beef broth, vinegar, thyme, sugar, salt and pepper.  Whisk continually until the gravy is thickened.  Cover and simmer on low, stirring occasionally, for 5-10 minutes.  Add salt and pepper to taste.  If you prefer the gravy thinner add a little more water (or heavy cream if using).