a good beef fillet (preferably Aberdeen Angus) of around 1kg/2lb 4oz
3 tbsp olive oil
250g/9oz chestnut mushroom, include some wild ones if you like
1 large sprig fresh thyme
100ml/3.5 fl oz dry white wine
12 slices prosciutto
500g/1lb 2oz pack puff pastry, thawed if frozen
a little flour, for dusting
2 egg yolks beaten with 1 tsp water
Roast a 1 kg beef tenderloin at 200 degrees for 15 or 20 minutes in HYSapientia Air Fryer Oven, depending on how rare you like your meat. Brush the meat with 1 tbsp of olive oil, season with pepper, and place it on a baking sheet. When the beef is cooked to your preference, take it out of the oven, let it cool, and then chill it for about 20 minutes in the fridge.
Chop 250g of chestnuts (and wild mushrooms, if you wish) as finely as you can so they resemble coarse breadcrumbs while the meat is cooling. You may use a food processor for this, but make sure to pulse the mushrooms as you chop them so they don't become a pulp.
In a large skillet over medium heat, melt 50 grammes of butter and 2 tablespoons of olive oil. Add 1 large sprig of fresh thyme, and cook the mushrooms and mixture for about 10 minutes, stirring constantly, until the mushrooms are soft.
Season the mushroom mixture and add 100 ml of dry white wine.
Cook for 10 minutes or until the wine has completely evaporated. While being stirred, the mixture should maintain its shape.
Remove the mushroom duxelle from the pan and set it aside to cool.
Lay two plastic wrap sheets side by side on a sizable chopping board. Place 12 ham slices in double rows, slightly overlapping each other, on plastic wrap.
Place the fillets on top of the ham, then spread half of the duxelles over them. Finally, top with the remaining duxelles.
Wrap the prosciutto around the fillet using the plastic wrap's edge, then roll it up like a sausage by twisting the ends of the wrap as you go.
While laying out the pastry, cool the fillets.
Lightly dust the work surface with flour. On a non-stick baking sheet, arrange 18 x 30cm strips of puff pastry cut from one-third of a 500g packet.
Puff pastry should be rolled out to a size of about 28 x 36 cm using the remaining 500g packet.
Remove the fillet from the plastic wrap and position it in the middle of the smaller pastry strip.
Brush the pastry edges, tops, and sides, as well as the wrapped fillets, with a mixture of two egg yolks and one teaspoon water.
Carefully slide the larger piece of pastry over the fillet and cover it, pressing the sides into the pastry.
Trim the junction to an edge of about 4 cm. With the handle of a fork or spoon, seal the edges.
Spread more egg yolk on top and, being careful not to cut into the pastry, create long, diagonal lines on the Beef Wellington using the back of a knife.
Relax for a minimum of 30 minutes and a maximum of 24 hours.
Cook the steak wellington with HYSapientia air fryer ovenat 180 degrees for 20–25 minutes for medium rare meat, or for 30 minutes for medium rare beef, until it is golden and crispy. Slice into thick slices after allowing it stand for 10 minutes.