Let the beef fillet freeze in the freezer for approx. 1/4 hour (the meat can then be cut better). Cut broccoli into small florets and wash. Boil up plenty of salted water. Cook the pasta in it for about 12 minutes. Add broccoli about 5 minutes before the end of the cooking time. Finely dice onion.
Cut fillet into thin slices. Heat oil in a pan. Brown the meat in it and take it out. Season with salt and pepper. Sauté onion in frying oil. Deglaze with beef stock and bring to the boil. Stir in sour cream. Add green pepper. Thicken sauce. Season to taste with salt. Warm up meat in the sauce.
Deglaze with beef stock and bring to the boil. Stir in sour cream. Add green pepper. Thicken sauce. Season to taste with salt. Warm up meat in the sauce. Drain pasta and broccoli, let drain. Arrange noodles, broccoli, beef fillet and pepper sauce together