Preparation: 20 minutes Cooking: 2 hours (dependent upon weight) plus 30 minutes resting time
1 whole aged forerib of beef
2 tbsp olive oil
Salt and freshly ground black pepper
For the sauce:
2 tbsp butter
1 tbsp oil
1 tbsp Dijon mustard
500ml crème fraiche
Salt and pepper
Preheat the oven to 220°C. Massage the whole beef joint with olive oil and season well with salt and pepper. Place in a roasting tray and cook in the oven for 30 minutes when the meat should be well-browned.
Turn the oven down to 180°C and open to door for a minute to allow it to cool quickly. Place the beef back in the oven and allow a further 15 minutes per 500g for medium rare, or 12 minutes per 500g for rare.
Remove from the oven and place on a warm plate or carving tray. Leave the meat to rest for a minimum of half an hour.
Just before serving, make the sauce. Fry the watercress in the butter and oil until wilted. Add the mustard and crème fraiche and gently bring to a simmer. Do not allow the sauce to become too hot as the crème fraiche may split.
Season to taste then serve alongside the beef with all the trimmings.