Mini Boeufs en Croute

Begin by making the filling well ahead, as it needs to be chilled before you use it.

Start off by soaking the porcini in boiling water for 20 minutes and while that's happening the onion and open-cap mushrooms will need to be chopped as finely as possible. If you have a food processor you can do this in moments; if not, use a very sharp knife and chop them minutely small.

When the porcini have had 20 minutes, squeeze out all the excess liquid, then chop them small as well. Now, in a medium saucepan, melt the butter and stir in the onions and mushrooms to get a good buttery coating, then season well with salt, pepper and a few gratings of fresh nutmeg.

What you need to do now is turn the heat to its lowest setting and cook, uncovered, allowing the juices from the mushrooms to evaporate slowly. This will take about 35 minutes altogether – stir it from time to time and what you should end up with is a lovely concentrated mixture with no liquid left.

Spoon the mixture into a bowl, cool and chill in the fridge.

A few hours before you want to serve the steaks, heat the beef dripping in the frying pan until it's smoking hot, or, as the chef who taught me to cook said, 'Hot as you dare!' Now place the steaks 2 at a time in the pan and give them 30 seconds on each side – what you're trying to achieve here is a dark, seared surface without cooking the steaks – then remove them to a plate.

Turn the heat off under the pan, but don't wash it, because you're going to need it again later.

While the steaks are cooling, cut the pastry into 4 pieces and roll each one out thinly to about a 7½ inch (19 cm) square; trim the edges to get a neat square and reserve the trimmings. As soon as the steaks are cold, brush them with a little brandy, season with salt and pepper, then lightly brush the surface of each pastry square with the beaten egg.

Reserve 1 tablespoon of the mushroom mixture for the sauce, place about an eighth of the remaining mixture in the middle of each square of pastry, then top with a steak.

Now place the same amount of mushroom mixture on top of each steak, then bring 2 opposite corners of pastry up to overlap in the centre, tucking in the sides as if you were wrapping a parcel, brush the pastry all over with more beaten egg and bring the 2 remaining corners up to overlap each other.

Be careful to seal the pastry only gently because, if you wrap it too tightly, it tends to burst open in the oven. If you like, you can use the reserved trimmings to make leaves for decoration.

Then, using a fish slice, gently lift the parcels on to the baking sheet, cover with a clean tea cloth and chill for at least 30 minutes, or until you're ready to cook them.

When you are, pre-heat the oven to gas mark 7, 425°F (220°C), pop them in the oven on a high shelf and cook for 25 minutes, which will give you medium-rare steaks. If you want them well done, give them 5 minutes more; if you want them rare, give them 5 minutes less.

While they're cooking, pour the wine and reserved mushroom mixture into the frying pan. Let it all bubble and reduce by about a third – this will deglaze the pan and you can then spoon a little of the reduction around each portion before it goes to the table.

One word of warning: you must have your guests seated and ready before this is served, because if the steaks wait around, they go on cooking inside the pastry.