Drizzle olive oil in cast iron pan.
Add butter, onions, and garlic and saute until onions start to turn translucent.
Stir in mushrooms, splash with liquid aminos and balsamic vinegar, and cook until mushrooms begin to soften.
Add beef, fry for a few minutes to heat through. Add more liquid aminos as needed.
Add water and bouillon, bring to a slight boil.
Let the simmer for a few minutes.
Add salt and pepper to taste.
Stir in flour and simmer for a few more moments. Sauce will begin to thicken.
Blend in yogurt.
Serve over mashed potatoes.