1. Soak black beans for 24 hours.
2. Boil until fully cooked tender but not mushy.
3. Remove water. Rinse.
4. Mash beans up or use processor and pulse so most of it is crushed but still chunky. Make large squares about the size of your hand and about 2-3 inches thick.
5. Air dry in warm and well circulated room on racks [near clean vents.] This process takes a long time [sometimes several weeks] and smells up your house. In the summer, you can hang them outside once they maintain their shape.
6. Once blocks are completely dried through, dust off/wash and place in brine made of filteredwater and salt of your choice. Lots of salt and lots of water so blocks are floating on top. This liquid will become your soy sauce. Too little salt does not allow the blocks to float and can cause molding. I keep mine outside and open the lid when the weather is nice so that it can breath. I put mesh around the opening to prevent anything from flying in. I also put a piece of charcoal in the brine. If takes away a lot of the smell and impurities. Leave this for approx. 6 months. You can taste the brine periodically to see if you like the taste. You can always stop earlier.
7. Once you are ready, remove moist blocks and put the brine through a sieve/cloth and boil. Let cool.
8. Place in glass jars (sterile). Puree bean blocks in food processor and place in jars and either put raw garlic paste or thick coating of salt over the top to prevent molding. This has to age at least a few months.
9. Open the lid and let natural sun hit it and form dry crust. Keep doing this when ever you can.
10. This intensifies the flavor and keeps it from molding.
11. When ready to eat, remove the top layer and use the inner paste as base for soups.
12. Home made soy sauce is less dark than the ones you buy in the market. When using black beans, you have the option of removing the skin. This will give you a lighter colored miso, more like the ones in the asian markets.
13. I have been making my own soy sauce and bean paste for years and just started the black bean one a year ago because of SCD.