Heat olive oil in a large skillet over medium-high heat. Add the beef slices and cook until browned. Remove from the skillet and set aside.
In the same skillet, add the chopped onion and garlic. Sauté until the onion is translucent.
Add the sliced mushrooms to the skillet and cook until they are tender.
Sprinkle the flour over the mushroom mixture and stir well to combine.
Gradually add the beef broth, stirring constantly, until the sauce thickens.
Reduce the heat to low and stir in the sour cream. Season with salt and pepper to taste.
Return the cooked beef to the skillet and simmer for a few minutes until heated through.
Serve the beef stroganoff over cooked egg noodles or rice, garnished with fresh parsley.
