Beef should be room temperature. Heat up the oven to 210c.
Pour the oil over the beef. Same with salt and pepper.
Sprinkle the flour over the top beef.
Warm up left oil. Fry beef for few minutes, all sides.
Take out the tray from the hob. Strew chopper onion around beef.
Put the beef in oven. Cook 15 min. set the oven to 180c.
Cook 20 min for rare beef, 30-35 for medium or 45 -50 for well done.
When the beef is cooked, cover it with foil for 20 min.