Rare roast beef and winter coleslaw

Method

1. Preheat the oven to 190°C/fan170°C/gas 5. Rub the beef with a little oil and season. Heat a frying pan until smoking hot. Add the beef and sear for a few minutes all over, to brown. Transfer to a roasting tin and cook for about 35 minutes for rare (or 45 minutes for medium rare). Set aside to rest for 20 minutes, then slice.
2. Meanwhile, discard the outer leaves of the cabbage, then core, shred and put into a very large bowl. Peel and core the celeriac and pears, and slice into long thin strips. Add to the cabbage and toss with the juice of 1 lemon. Set aside.
3. Make a thick mayonnaise by beating the egg yolk and mustard, then slowly whisking in the oil. Thin down with enough of the remaining lemon juice, then season and toss with the cabbage. Serve with the beef.