Step 1

Heat oven to 180C/160C fan/gas Season the steaks well on all sides, then heat a frying pan with 2 tsp of the oil. Brown the steaks well on all sides, then transfer to a snug casserole or narrow, deep baking dish.

Step 2

Tip the Guinness into the frying pan and bring to a simmer, scraping up any stuck meaty bits. Pour over the steaks along with the stock cube, Worcestershire sauce, brown sauce, bay and skin-on halved shallots (leave the skins on to save time – they are removed from the sauce later). Cover the dish tightly with foil first, then add the lid (or a flat baking tray). Bake in the oven for 3 hrs until the meat is meltingly tender. Can be done up to 1 day in advance, then cooled and chilled.

Step 3

For the chips, 1 hr before serving, turn up oven to 200C/180C fan/gas Bring a large pan of salted water to the boil while you cut the potatoes into as many 3cm fat chips (save the trimmings in a bowl of water and use for mash another night). Par-boil for 3 mins, then drain and let steam-dry for a few mins. Tip onto a baking tray, toss with the polenta or flour and some sea salt, then drizzle over the oil and toss again. Roast for 45 mins until really crisp and golden.

Step 4

When the chips have 20 mins left, lift your steaks from their cooking liquid and use a few sheets of baking parchment to wrap them in a parcel, followed by foil. Put on a low shelf in the oven to heat through for 20 mins. Meanwhile, strain the cooking liquid into a pan, discarding the herbs and shallots. Boil fiercely until reduced by three-quarters. Taste for seasoning, then keep warm.

Step 5

Whisk the chopped shallot, horseradish, remaining 2 tsp oil, vinegar and 1 tsp water with some seasoning, then use to dress the watercress.

Step 6

To serve, carefully open the meat parcel over your saucepan to catch any juices, and add your beef to the sauce to coat. Stack your chips between 2 plates and add a pile of dressed watercress. Lift a steak onto each plate and spoon over the syrupy juices. Any extra can be served in a jug on the side.