Beef And Mushroom Stroganoff

• 1 onion (sliced)
• 350 gr beef tenderloin
• 240 ml beef broth
• 120 ml nonfat sour cream
• 80 gr pkg mushrooms (sliced fresh)
• 55 gr egg noodles (uncooked)
• 16 gr pillsbury best all purpose flour
• 5 ml oil
• 1 gr salt
• 1 gr pepper