Roast beef with port & blackberry sauce

The evening before cooking (up to 2 days ahead), brine the beef. Whizz the salt and 5 bay leaves in a small food processor until finely ground to a pale green shade. Put the beef in a large, rimmed glass or ceramic baking dish and coat evenly with the salt mixture. Cover loosely with foil and chill until ready to cook.

Preheat the oven to 150°C, gas mark 2. Put the remaining 5 bay leaves in the centre of a deep roasting tin with the onions, cut-side down. Wipe off and discard as much brine as possible from the beef and pat dry with kitchen paper. Rest the beef on top of the onions and coat with the oil.

Roast for about 2 hours for rare (50°C on a meat thermometer), 2 hours 5 minutes for medium-rare (55°C) and 2 hours 10 minutes for medium (60°C). Transfer to a serving platter and rest for at least 30 minutes, loosely covered with foil.

Meanwhile, make the sauce. Put the roasting tin on the hob over a high heat. Sprinkle in the flour and cook, whisking constantly, for 3-4 minutes until just starting to catch. Pour in the port and boil rapidly, scraping the base of the pan as you go, until thickened again (2-3 minutes). Add the stock and redcurrant jelly, whisking for another 1-2 minutes, then pass the sauce through a sieve into a medium pan, pressing to extract as much juice as possible (discard the onions but keep the bay leaves for decoration, if liked). Add any resting juices from the beef, along with the blackberries. Simmer briskly for 2-3 minutes until the sauce is thickened to your liking and the berries have burst a little; season if needed. Thinly slice the beef and serve with the sauce plus your choice of sides.