600 g/11⁄4 lbs fillet of beef, in one piece
Salt and pepper
1 knob butter
4 garlic cloves
1 tbsp thyme, chopped
1 ready-rolled chilled sheet of puff pastry, approx.300 g/11 oz
50 g/2 oz grated Västerbottensost
1 egg yolk
300 g/11 oz celeriac
1 chicken stock cube
500 ml/18 1⁄2 fl oz water
Preheat the oven to 200°C/400°F/Gas 6. Season the fillet of beef with salt and pepper. Sear each side of the beef until golden brown in a little butter in a hot frying pan. Slice the garlic thinly and strip away the stalks from the thyme. Place the fillet of beef slightly off-centre on the puff pastry sheet and scatter garlic, thyme and cheese around the meat. Roll the beef up in the pastry and seal the join securely. Glaze with egg all the way round and bake in the oven approx. 20-30 mins (until the internal temperature is 60°C/140°F). Allow the beef Wellington to rest for about 15 mins before serving.
Peel celeriac and potato and cut into small pieces, cook in chicken stock. Drain and reserve the chicken stock. Mix to a smooth purée, adding more stock if necessary. Season with salt and pepper. Cut the beef Wellington into slices. Serve with a dollop of celeriac purée. Boiled beans and cherry tomatoes tossed in butter also make good accompaniments.