Delia Smith's Boeuf En Croute

Pre-heat the oven to gas mark 5, 375F (190C).

To make the flaky pastry, take the fat hard from the fridge, weigh out the required amount, then wrap it in a piece of foil and place it in the freezer for 30-45 minutes.

Meanwhile, sift the flour and salt into a mixing bowl. When you take the butter or margarine out of the freezer, hold it in the foil, dip it into the flour, then grate it on a coarse grater placed in the bowl over the flour.

Keep dipping the fat down into the flour to make it easier to grate. At the end you will be left with a lump of grated fat in the middle of the flour, so now take a palette knife and start to distribute it into the flour - don't use your hands - just keep trying to coat all the pieces of fat with flour until the mixture is crumbly.

Now add enough water to form a dough that leaves the bowl clean, using your hands to bring it all gently together. Pop the dough into a polythene bag and chill it for 30 minutes - this time in the fridge.

Meanwhile, you can be trimming the meat, removing any excess fat and bits of sinew. Brush it all over with some brandy, rub 10g (½oz) of butter over it, place it in a roasting tin and cook for 40 minutes (basting it now and then with the juices). Then remove from the oven and leave to get quite cold.

Chop the onion and mushrooms as finely as possible, then melt the remaining butter in a small saucepan.

Stir the onion into it, allow it to cook for 5 minutes, then stir in the mushrooms and continue to cook the mixture over a gentle heat (without a lid) for about 20-25 minutes, so that the juices will be drawn out of the mushrooms and onion and evaporate, leaving you with a concentrated mixture.

The final mixture mustn't be too liquid. Season it then with salt, pepper and a grating of nutmeg.

When both the meat and mushroom mixture are ready, preheat the oven to gas mark 8, 450F (230C).

Take the pastry from the fridge and roll it out to a rectangle approximately 35 x 25cm (14 x 10 inches).

Trim the edges (keep the trimmings for decoration), then spread half the mushroom and onion mixture over the centre. Place the fillet on top and the rest of the mixture on top of that: pat it down into a good shape.

Now brush the edges of the pastry with beaten egg, and wrap the pastry like a parcel around the meat - if necessary brush the edges at each end and fold them over again.

Place the whole lot on a baking sheet, brush all over with beaten egg (including any decorations you have added), and bake in the oven for a further 30 minutes.

This should be served cut into thick slices, together with some gravy made with the meat juices left in the roasting tin and some red wine.