This is just an excuse to indulge in the luxury of Boletus edulis, in a form that feels substantial enough to call dinner.You can purchase the filo dough in most delis and mediterraneam markets. It comes in a stack of large, thin sheets that dry out very quickly, so keep a clean damp cloth around to cover the stack while you are working. This will keep the sheets from cracking and make them easier to work with.
Beat the eggs and retain a few tablespoons for use at the end. Pour the boiling water over the dried mushrooms and let them sit for a while to cool. Put all of the ingredients (except the filo dough and extra bit of egg) into a food processor and grind into a paste. Separate 6 layers of filo dough together in a sheet (typically about 12" square), and cut the sheet into 4 strips (about 4" x 12") with a pair of scissors, keeping the remainder of the filo covered with a towel. Put about 2 tablespoons of the mushroom paste into the base of the strip, and fold upwards end-over-end in a triangle like a flag. Brush a bit of melted butter into the folds occasionally to moisten and glue it all together. Put a bit more butter especially on the last flap of the fold to seal it shut. Assemble the pockets onto a baking sheet and brush the tops with a bit of egg.
Bake at 300º F for 55-60 minutes on the cookie sheet, until brown and crusty on the outside. Some will ooze from the inside - that's OK. One package of filo should make about 16 pockets.