Slice of Beef Wellington

Clean and chop the mushrooms. Peel and finely dice the onion. Heat 2 tbsp butter and sweat the onion until translucent. Add the mushroms and sweat until all the liquid has evaporated. Remove from the heat and leave to cool. Trim the meat and season with pepper. Heat the clarified butter and brown the meat on all sides over a fairly high heat. Take out of the pan and leave to cool. Mix the onions and mushrooms with the crème fraiche, mustard and thyme. Season with salt and pepper and add the sherry. Put into the refrigerator until needed. Preheat the oven to 200 °C. Spread out the puff pastry, roll out to a rectangle and place the meat on top. Spread the mushroom mixture on the meat and carefully bring the pastry up and around the meat, pressing the edges together firmly on the joins. Rinse a baking tray with cold water, place the beef Wellington on the tray and brush with egg yolk. Bake in the preheated oven for about 30 minutes, until golden brown. Switch off the oven and allow the meat to rest in the oven for at least 15 minutes before serving. To serve, slice fairly thickly and garnish with tomatoes and parsley.