Soak 1.5 lbs beans for 6 hours in water with a little baking soda
Change water halfway through
Preheat immersion circulator/sous vide chamber to 110 F
Pressure steam for 20 minutes
Spread into wide flat container
Stir old nattō into 1/2 cup water, mix evenly into beans
Lay plastic wrap snugly against beans, poke many holes
Cover tightly with tin foil, poke a couple holes around edges
Poke corded probe thermometer into center from edge
Float in immersion circulator chamber for approximately 20 hours
The temperature in the beans generally kept about 2 degrees less than the chamber. I think we want the early fermentation to happen at 108 F and then cool to 100 F, so I tried to keep adjusting it based on that. Anyway, the result was pretty tasty!! The bacteria seem to take well to black-eyed peas. Might have been a little less stringy than "normal", but still delicious!