ahh i see, wish i could be of more help, ive never tried this, but ive made many teas, and boiled them many times so i would think you could just start making a tea from them
and boil the tea down 100% into a gunk. Than any moldy funkiness from the aged shrooms should
be destroyed by the boiling process anyways, then maybe cap up the gunk and eat it..
It would be a great experiment, and im really curious to see if it works
edit: your vinegar extract idea is good too, either way, let us know how it works out