Prepare all of the ingredients.
Finely chop the shallot.Scoop the marrow from the bone using a spoon and cut it into chunks.
Pour the oil into the bowl.
Brown beef for 2 minutes on each side. Remove. Gently fry shallots in half the butter. Add the wine, beef stock and cornflower.
Mix until boiling. Season. Add the bouquet garni, tournedos and marrow.
Cooking time: 2 min.
Remove the beef, bone and bouquet garni. Add the butter and whisk. Serve!