Place the beans in a bowl and add 1 litre of water. Cover and leave to soak in the fridge overnight.
Drain the beans and transfer them to a large pan. Cover with water and bring to the boil; then reduce the temperature, add a lid, and simmer until the beans are soft. NOTE: This takes about 45 minutes for fava beans, but may take several hours for soya beans.
When the beans are cooked, pour them into a colander and drain.
If you'd like a smooth miso, blend the beans with a hand-held blender or food processor.If you prefer a chunky miso, roughly mash the beans with a fork.
Once the beans have reached a consistency you're happy with, leave to cool.
Mix in the packet of koji and 60g of salt.
Form the miso into small balls. If the balls crack they are too dry, so will need a little bit more water mixed in.
Squash the balls into a clean jar, ensuring all pockets of air are removed.
Once all the miso has been squashed into the jar, sprinkle the surface with the remaining 2g salt. Then cover and transfer to a warm place (25-30'C) for 10 days.
After 10 days, gently scrape the salt from the surface and taste the miso. If it is the required strength, transfer to a fridge and enjoy! It will keep in a fridge for several months. If you prefer the miso a bit stronger (or the temperature has been lower than 25'C) then replace the salt topping and leave for another few days.
Non-iodised salt, is a salt that does not contain additives which may inhibit fermentation