I never add plain water to pot roast, the liquid I use is beer/ale and
whatever exudes from the veggies... if a bit too soupy I add a corn
starch/Wondra slurry.
Fresh 'shrooms exude a lot of water, and sometimes I'll use canned and
add that water too. But mostly I use dehy wild 'shrooms, I add back
the rehydrating liquid except for the dregs which contain
sand/schmutz. I always keep a selection of various dehy 'shooms.
I rarely buy those teensy containers of fresh button 'shrooms, those
are flavorless besides being way over priced.
Mostly for pot roast I use top round, chuck is too fatty, and it tends
to fall apart into tough strings, what cooking dummys call pulled
meat... I call that Kennel-Ration.
The trick to pot roast is that it must be as sliceable as regular
med-rare roast beef. An easy way to accomplish that is to remove the
meat from the pot and place it in a covered dish in the fridge to cool
over night, The next day that cooled pot roast will very easily be
sliceable as thinly as one wants, and then place the slices back into
the pot with the veggies to reheat. Cold pot roast is very easy to
slice... I actually enjoy a cold sliced pot roast on seeded rye with
horsey sauce... a fistful of fermented garlic dills on the side makes
it Superman... but then WTF do yoose TIADer fast foodies know.