As per the instructions given by ‘canucklehead’ on eGullet’s forum, here is how I have made soy sauce at home:
Step 1: Soak 500 g dry soy beans overnight
Step 2: Boil soy beans until soft and crumbly
Step 3: Coarsley chop in food processor and mix with 300 g (whole wheat in my case) flour. I used whole wheat as it is less processed than white flour, meaning it likely has a greater diversity of microorganisms surviving in it.
Step 4: Form bean/flour mix into a loaf and slice into patties about 1 cm in thickness
Step 5: Lay out ’soy patties’, cover with damp paper towels, and loosely wrap in cling wrap.
Step 6: Monitor patties, dampening towels as needed. Let sit for 5 – 10 days, until well covered by mold. In my case, the patties did not appear to be doing much for several days, but began to smell like my salt-risen bread starter (Clostridium bacteria). Then over two days the patties became completely covered in various molds:
