A fine sourdough really makes this dish, I suspect without it there would be no hard feelings whatsoever, however the backbone, the texture and that tiny hint of sour just carries that whole mushroom mix on to the next rung of the tasty ladder. Great bite provided by the cabbage here, which, though it is not currently in front of me, I believe was not the originally listed green. Oyster mushrooms used, and very nice they were too.
From 3 2 1, pg. 256