beef, mushrooms, butter, onion, salt, flour, beef broth, sour cream, egg noodles Recipe: 1. Melt butter in a large saucepan over medium heat. Add onion and mushrooms; cook and stir until the vegetables are soft, 5 to 7 minutes. 2. Sprinkle flour over the vegetables and stir to coat. Pour in beef broth and add salt. Bring the mixture to a simmer and cook until thickened, about 5 minutes. 3. Stir sour cream into the saucepan; cook until heated through, about 1 minute. Do not allow the mixture to boil. 4. Meanwhile, cook egg noodles in a large pot of boiling water until tender, about 10 minutes. Drain and stir into the saucepan with the beef stroganoff. Serve hot.