Cut the meat against the grain into thin strips (about ⅕ inch thin) and place them in a bowl.
1 pound beef tenderloin filet
Add 1 Tbsp of flour to the meat and mix with a spoon or hands until meat strips are evenly covered.
3 Tbsp flour,
Heat olive oil in a large skillet over high heat, I recommend using a nonstick skillet.
3 Tbsp olive oil
Add beef strips and cook for about 90 seconds until meat browns. Don't stir too often, just once should be enough. If the pan is overcrowded, the meat will steam rather than brown.
Remove browned beef to the plate and set aside.
Turn the heat to medium and add butter and sliced onions to the pan. Add salt and sauté for about 4 minutes, stirring. Onion should be soft and translucent.
2 Tbsp butter, 1 medium onion,, ½ tsp salt
Add minced garlic and cook for 30 more seconds.
2 cloves garlic,
Add sliced mushrooms and black pepper, cook for 5 more minutes, stirring from time to time. Add red wine and cook for 30 more seconds.
¾ pounds brown mushrooms,, ¼ tsp black pepper, ¼ cup dry red wine
Transfer meat back into the pan, add bouillon, Worcestershire sauce, Dijon mustard. Mix, bring to a simmer and cook on low heat for 5 minutes.
2 cups beef bouillon, 1 Tbsp Worcestershire sauce, 1 Tbsp dijon mustard
Add remaining 2 Tbsp of flour to sour cream and mix until no lumps remain. To make it easier you can add 2 Tbsp of cooking liquid from the pan.
3 Tbsp flour,, ⅔ cup sour cream
Add sour cream and flour mixture to the pan, stir, and cook until the sauce thickens. Taste and add more salt or pepper if needed.
Serve with your favorite egg noodles and chopped green onions or parsley on top.
chopped green onion or parsley,