Reduce the wine by a quarter in a saucepan, add the veal stock, allow to reduce (the sauce should be syrupy), add the butter and whisk in. Pan-fry the beef fillet on a very high heat on all its surfaces (just to colour, not to cook).
Rest the beef for 5 minutes. Cut into very thin slices, dress with the wine sauce, chopped hazelnuts, julienned radishes and chiv