Fillet of Beef with Traditional Champ, Slow-Roasted Mushrooms and Cabbage and Bacon, Served wth Stout Gravy

My best friend Jeff as arrived from the States and we made a conscious decision to really push the boat out in terms of meals. This is from Great British Menu and was pretty awesome. We used the leftover champ to make bangers and mash the next day. Anyhow, I don't have a lot of time to write... just know that this was very good and pretty easy to throw together.

600 g tightly packed Savoy cabbage
rapeseed oil
4 rashers of back bacon, preferably Pat O'Doherty's black bacon, rinds removed, cut into lardons
4x160 g fillet steaks, preferably Kettyle Northern Irish
salt and pepper
SLOW-ROASTED MUSHROOMS
50 ml rapeseed oil
4 garlic cloves, crushed
leaves of 1 sprig of rosemary, finely chopped
leaves of 3 sprigs of thyme, finely chopped
4 flat cap mushrooms, stems removed and caps peeled
CHAMP
1.5 kg potatoes, preferably British Queens, peeled
100 ml whipping cream
4 spring onions, chopped
50 g salted butter
GRAVY
350 ml Irish stout
3 tablespoons redcurrant jelly
sprig each of rosemary and thyme
2 garlic cloves, roughly chopped

Preheat the oven to to 130C/110C (fan).

First prepare the mushrooms. Mix together the oil, garlic, rosemary and thyme. Arrange the mushrooms gill-side up on a non-stick baking tray, pour over the oil and herb mixture, and season with sea salt and freshly cracked black pepper. Roast the mushrooms for 1 hour.

Meanwhile, cook the potatoes for the champ in boiling salted water for about 20 minutes until soft, then drain and mash until all lumps are eliminated. Bring the cream and spring onions to the boil in the pan, add the mash and beat until smooth. Season and add the butter. Set aside in a warm place.

Cut the cabbage into six or eight wedges. Discard the thickest part of the core, but leave a little to help hold the leaves together. Heat a little oil in a frying pan until it is very hot and fry the bacon until crisp. Add the cabbage and mix with the bacon, then reduce the heat, cover the pan with a lid and cook slowly for 5-10 minutes or until the cabbage is tender. Season and set aside in a warm place.

Remove the mushrooms from the oven and keep warm. Increase the oven temperature to 200C/180C (fan) and place a baking tray inside to heat up.

Season the steaks all over. Heat a heavy frying pan until red hot, then add a little oil. Place the steaks in the pan and sear all over (top, bottom and sides). Transfer the steaks to the hot tray and finish cooking in the oven, allowing 4-5 minutes for medium-rare meat. Remove the steaks from the oven and leave to rest in a warm place while you make the gravy.

Deglaze the steak juices in the frying pan with the stout, then boil to reduce by about three-quarters. Add the redcurrant jelly, rosemary, thyme and garlic, and simmer for 5 minutes. Strain and season, then keep hot.

To serve, put a mushroom in the middle of each warmed plate. Top with cabbage and bacon, and then a steak. Spoon a quenelle of champ on top of each steak, and drizzle the gravy around the plate.