In large saute pan, heat up butter and olive oil. Add onion and mushrooms. Saute for 5-7 minutes until softened and onions are starting to brown slightly. Add in garlic in the last minute.
Sprinkle with flour, stir, and cook flour for 2-3 minutes.
Stir in beef broth, scraping bottom of pan to release brown bits. Whisk. Add in vinegar, thyme, salt and pepper. Simmer gravy, whisking occasionally for 5-8 minutes until thickened.
Ladle over mashed potatoes or meat of your choice. Enjoy.
Notes
Store leftovers in fridge for up to 3 days.See post for substitution option for gluten free.Serve with Pretzel Encrusted Schnitzel.