- 2 2/5 cups (3 Japanese cups) dried black soybeans
- 1 tsp baking soda
- 2 2/5 cups (3 Japanese cups) and 6 tablespoons sugar
- 1 3/5 cups (2 Japanese cups) water
- Rinse the beans. In a bowl, add the beans, baking soda and enough water to
cover the beans by 2 inches. Leave it overnight.
- Rinse the beans. Cook beans over medium heat with enough water to cover the beans by 2 inches.
Boil the beans for 5 minutes and then drain them (this is to discard the bitterness). Return the beans to the cooking pot,
add new water and return it to the heat. When it starts to boil, skim the foam and turn down the heat to a simmer.
Cover and cook
for 5 to 6 hours, adding more water if necessary. When the beans are done cooking, they should be very
tender and yet they will still hold their shape.
- Cool down until lukewarm and slowly rinse with cold water and drain.
- In a separate bowl mix sugar and 1 3/5 cups water. Add beans and refridgerate for
3 days, mixing in 2 tablespoons of sugar every 24 hours. Ready to serve.
 You can find dried black soybeans at most Japanese or Asian supermarkets.
Please note that black soybeans are different from Azuki beans.
 In the Japanese tradition, people would wrap
3 rusty iron nails in a cloth and put it in a pot to cook with beans. The oxidized iron makes the beans dark and shiny.
However, cooking with iron nails is not necessary for this recipe.