

If you have trouble with the soaking, black beans do very well with a “quick soak”.
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Cover them with water about twice the depth of the beans. Add about 1 teaspoon (~5 ml or 5-7 g) salt.
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Bring to a boil and keep it boiling for 2 minutes. Then cover and turn off the burner/hob. Let soak for 1-2 hours.
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Add any extra seasonings now (but nothing acidic). Then bring back to a boil and then simmer until soft. Adjust seasoning and you’re done.
They should take much less time than cooking from dry. How long will depend on the beans. Older beans can take much longer, but most should be soft in 1 hour or so.
I’m not a potatologist, but it seems like it should be fine to let it grow in there for a couple more weeks. It’s happy there, and that’s the main thing.
Then transplant it to a big bin/pot/raised bed or the ground outside. If it’s root bound just cut down on the sides of the root tangle and detangle them a bit before planting. Put a big clear plastic tub/tote over it at night if it will be frosty.