500g/1lb 2oz chestnut mushrooms, finely chopped
20g/ΒΎoz dried porcini mushrooms or large morels
4 small shallots, peeled and very finely chopped
large handful fresh thyme leaves
plain flour, for dusting
salt and freshly ground black pepper
2 tbsp vegetable oil
knob of butter
300ml/10fl oz double cream
1 free-range egg, lightly beaten
500g/1lb 2oz packet ready-made puff pastry
4 x 180g/6oz slices beef fillet
generous dash medium sweet sherry (optional)