Heat half the oil in a frying pan and quickly seal the venison for about 2 mins on each side until browned. Remove the meat from the pan, brush all over with the mustard and leave to cool. Mince the mushrooms in a food processor. Place the pan back on the heat with the rest of the oil and add the mushrooms. Season with salt and pepper and fry over a high heat for 5 mins until the excess moisture has evaporated and you have a thick paste. Season, transfer the mushrooms to a bowl and leave to cool. Lay 2-3 large sheets of cling film overlapping each other on a clean surface. Lay the slices of prosciutto overlapping lengthways in 2 rows of 3. Sit one of the pieces of venison in the middle of the prosciutto. Press the mushrooms over the venison and sandwich with the other piece of venison. Roll into a tight package (see step-by-step images above) and leave to chill in the fridge. Lay out another couple of pieces of cling film. Trim the pancakes into squares and lay them overlapping on the cling film. Remove the cling film from the prosciuttowrapped meat and place the meat on top of the pancakes. Roll up tightly again in cling film, then place in the fridge to hold its shape. Roll the pastry out to a large rectangle big enough to easily wrap the meat in, then brush all over with egg yolk. Unwrap the cling film from the pancake-wrapped venison and roll to completely encase in the pastry. Tuck the ends in and trim any excess. Lay out more cling film and finally roll into a tight package to get an evenly thick log. Tie the ends of cling film to keep the package tight and leave in the fridge overnight or in the freezer for an hour. Can be made to this point up to a day in advance. When ready to cook, heat oven to 220C/200C fan/gas 7. Remove the cling film and brush the Wellington all over with egg yolk. Sit it on a baking tray lined with baking paper and lightly score in a feathered fashion. Bake for 50 mins for medium rare, dropping to 200C/180C fan/ gas 7 if the pastry becomes too brown. Remove from the oven to rest for 20 mins. If you prefer the meat well done, turn oven off after 40 mins and leave to rest inside. Trim the end of the pastry, carefully carve in slices about 3-4cm thick and serve. To make the pancakes for the Wellingtons, tip 100g plain flour into a bowl. Beat 1 egg with 250ml milk and gradually whisk into the flour until smooth. Stir in some snipped chives and a handful of chopped flat-leaf parsley just before cooking, then heat a drop of oil in a large non-stick frying pan and swirl around some of the batter to make a thin pancake. When the pancake is done, make another 3 and set aside. The pancakes can be made 2 days in advance. For a creamy mash, chunk 1kg floury potatoes. Place in a pan of cold salted water and bring to the boil. Simmer for about 15 mins until completely tender, then drain and return to the pan over a low heat for a few mins to dry out. Press the potatoes through a ricer and gradually add 150ml warm double cream and 50g butter. Season to taste and serve, or leave to cool and reheat in a pan or microwave with a touch more cream and butter. The mash can be made a day in advance. For the carrots, peel and trim 24 baby carrots (a mix of white and orange if you can find them) but keep them whole. Boil for 2-3 mins in salted water until just tender, then drain. Heat a large knob of butter in a frying pan and sizzle the carrots for 8-10 mins until golden. Serve the carrots or cool and reheat in a pan with a touch more butter or in the microwave. The carrots can be made a day in advance. To make a delicious port sauce, sweat 1 finely chopped shallot in a little butter with a thyme sprig. Pour in 300ml port and reduce by two-thirds, then add 600ml fresh chicken stock and reduce again by two-thirds until syrupy. Strain into another saucepan ready to be reheated. The sauce can be made 2 days in advance and reheated in the saucepan, adding a splash more stock if too thick.
