Preheat fan-forced oven to 210°C (230°C for non fan-forced)
Place roast a large, heavy-based roasting tray.
Season the meat with good quality sea salt just prior to cooking.
Make a trivet by roughly chopping equal amounts of onion, carrot and celery plus a bay leaf, sprig of thyme and a few black peppercorns.
Place the beef fat side up onto the trivet.
Place in the centre of the oven and roast for 20 minutes, then reduce the temperature to 160°C (180°C non fan-forced). Continue roasting for 12-15 minutes per 500g reaching a core temperature of 52°C before resting for a medium rare finish.
Remove from the oven, put onto a clean tray and keep warm by covering with a sheet of foil. Rest for a minimum of 20 minutes before carving, leaving the roasted vegetables in the tray for the gravy.
For the gravy, make up 500ml of beef stock, then deglaze roasting tray with this stock stirring in all the caramelized juices from the tray. Next, pass through a fine sieve pushing all the juices from the vegetables into a clean saucepan. Bring to a simmer and thicken if required by whisking in a teaspoon of cornflour mixed with a little cold water and reduce till you reach a rich, glossy gravy.