Step 1

SEAR THE MEAT: Heat the oven to 220°C / 425°F / Gas Remove any silver skin from the tenderloin and trim off any thin end. Season the tenderloin well on all sides with salt and pepper, then heat the oil in a large frying pan until very hot. Sear the pork on all sides, then remove from the pan and set aside.

Step 2

SAUTÉ THE VEGETABLES: Turn the heat to medium and melt the butter in the frying pan. Cook the mushrooms, onion and thyme until softened and golden brown, around 8 minutes. Season with salt and pepper, then deglaze the pan with the white wine, scraping up any browned on flavour from the pan with a wooden spatula. Cook until the liquid has evaporated, then remove from the heat and set aside to cool.

Step 3

ROLL AND WRAP IN PASTRY: Roll out the pastry to an approx 30cmx30cm square, then lay the slices of prosciutto on top, slightly overlapping. Brush with the mustard, sprinkle with the sage leaves, then spread the mushroom and onion mixture evenly over the prosciutto. Place the pork on top of the mushrooms, then roll up the pastry, tucking the ends underneath.

Step 4

DECORATE AND GLAZE: Transfer to an oven tray lined with baking paper, decorate with any pastry offcuts if you like, then brush well with the beaten egg.

Step 5

COOK THE PORK WELLINGTON: Bake in the preheated oven for 30-35 minutes until golden brown (see note).

Step 6

MAKE THE SAUCE: While the pork wellington is cooking, prepare the sauce. Heat the butter in the same frying pan that you used for the mushrooms until melted. Gently cook the onion for 5 minutes until softened, but not browned.

Step 7

REDUCE THE SAUCE: Stir in the mustard and cook for 1 minute, then pour in the chicken stock and white wine. Bring to a simmer, stirring, then stir through the cream and thyme. Cook for 5 minutes until thickened slightly, then season to taste with salt and pepper. Remove from the heat, cover and keep warm.

Step 8

SLICE AND SERVE: When the pork is cooked, remove from the oven and allow to rest for 5 minutes before cutting with a serrated knife and serving. Serve with green beans and the creamy mustard sauce.