Herb-roasted fillet of beef with horseradish potatoes

Serves 4

This calls for a good chunk of beef, like an aged rib-eye stripped of the outer fat, leaving you with a nicely marbled eye of meat which should melt in your mouth.

1 rib-eye of beef, off the bone, weighing about 1-1.5kg, tied
Maldon sea salt and freshly ground black pepper
Vegetable oil or dripping for roasting
2tbsp chopped parsley
1tbsp chopped thyme leaves
¹2tbsp chopped rosemary
1tbsp grain mustard
4 large onions, peeled and cut into 3 thick slices

for the horseradish potatoes

500g roseval or charlotte potatoes, cooked in their skins and scraped
1tbsp horseradish sauce
4 spring onions, finely chopped
Salt and freshly ground black pepper
2-3 tbsp good quality mayonnaise
1tbsp crème fraîche

Pre-heat the oven to 220ºC/430ºF/gas mark 7. About 10 minutes before you put the beef in, heat a couple of tablespoons of vegetable oil or dripping in a large roasting tray until it's beginning almost to smoke (you can do this on top of the stove). Season the rib-eye with some sea salt and pepper and roast for 10 minutes, then turn it over to seal the meat and keep the juices in. Remove the tray from the oven and take the beef out of the roasting tray. Spread it with the grain mustard on all sides, mix the herbs together and rub them all over the beef. Put the onions in the middle of the roasting tray and put the beef on top, then return to the oven. Allow 30 minutes per kilo for rare; 45 minutes for medium to well done.

Baste the meat regularly with the pan juices. Once cooked remove the beef from the tray and leave to rest on a plate for 10-15 minutes. Add a couple of tablespoons of water to the roasting tray and put on a medium flame on top of the stove. Stir with a spoon a couple of times to remove any residue from the bottom of the pan, then transfer the onions and any juices to a blender. Blend to a coarse consistency, season with salt and pepper if necessary then transfer to a serving bowl. This sort of roasted onion soubise goes particulary well with the beef.

Put the potatoes into boiling salted water and simmer for 10-15 minutes, drain and, when they're cool enough to handle (but not cold), peel or scrape off the skin. While they are still warm, roughly crush the potatoes with a fork (you want to keep some lumps). Meanwhile, mix the horseradish, spring onions, mayonnaise and crème fraîche together in a lard bowl, season with salt and freshly ground pepper, then fold in the crushed potatoes.

Serve the beef, preferably still warm, sliced into 1 cm slices with the potatoes and onion sauce served separately.