In a large pot, heat the oil over medium-high and add the mushrooms and cook until brown. Remove to a separate plate.
Add beef to the pan and cook for about 7 minutes or intil about 80% of the way cooked. Drain any excess greaseu
Add the onions and garlic, cook for a few minutes until soft and beef completely cooked.
Add in the seasonings and the flour, mix and cook for about a minute.
Pour in the chicken broth, scraping the bottom of the pan as you go, and cook until liquid is mostly gone.
Pour in beef broth and bring to a simmer. Add in the mushrooms and noodles. Cover and let simmer on low, gently stirring a few times until noodles are cooked.
Remove from heat and stir in sour cream.
Video
Notes
Don't skip the flour since it helps thicken up the sauce.
Substitute the sour cream for plain Greek yogurt or even cream cheese for a thick, creamy sauce.
Top with sliced green onions for added flavor and color.