Sprinkle beef tips evenly with salt and pepper.
Brown beef in hot oil in a large skillet over medium-high heat; add onions and mushrooms, and saute, 3 to 5 minutes or until tender.
Stir broth, tomato paste, and mustard into beef mixture. Cover, reduce heat to low, and cook 1 hour or until beef is tender.
Cook noodles according to package directions; drain.
Combine sherry and flour; stir into beef mixture, and cook, stirring constantly, until thickened. Stir in sour cream. Serve over hot egg noodles; sprinkle with parsley, if desired.
Walter C. Lund, Sr.