Mushroom and gruyere parcels (the return of)

This is an improved version of an earlier recipe (which I shall keep up here as a 'quick' version - this one takes longer to prepare).  These are great party food, and are popular at our Silent Film Club nights. 'The first rule of Silent Film Club is you do not talk about Silent Film Club...'!

Makes about 24 mini parcels

300g fresh mushrooms, sliced
10g dried porcini mushrooms
1 onion, finely chopped
2 cloves garlic, bruised and chopped
150g gruyere cheese, grated
handful of fresh chives, chopped
1 pack ready rolled puff pastry
15g unsalted butter
couple of dashes of soy sauce
olive oil
juice of half a lemon
1 beaten egg to glaze
salt and black pepper to taste

Rehydrate the dried mushrooms in just enough cold to cover an hour beforehand.
Heat a frying pan and add a lug of oil.  Fry the chopped onion over a medium-high heat until starting to caramelise.  Empty the fried onion into a bowl and set aside.
Turn the heat down a little and put the butter into the pan.  When foaming, add the chopped mushrooms and a dash of soy sauce. Cook, stirring frequently, over a medium heat until the mushrooms start to give up their moisture.  When they've started to colour and have reduced in size to about two thirds of their original volume, empty them into a bowl (with the onions) to cool. Depending on the size of your pan, you'll probably have to cook the mushrooms in a couple of batches.
Into a food blender, place the garlic, the onions and fried mushrooms, the rehydrated mushrooms and most of the hydrating liquid (leave the last bit as it will have sediment in it).  Pulse a few times in the blender until the mixture has a thick tapenade-like consistency.  Add the cheese, chives, lemon juice and salt and pepper to taste.  Mix well.
Cut the pastry into about 24 squares and put a spoonful of the mushroom mixture onto the centre of each. Fold the corners up carefully to make each a little parcel (they may open up as 'crowns', but will still taste lovely). Brush with the beaten egg, and bake in a pre-heated oven (180 C) for about 25 or until golden brown.

(If you have any mushroom mixture left over, it goes well stirred through pasta.)