Place the wood ears in a bowl and pour in enough hot water to cover.
Peel and thinly slice the onion.
Peel and grate the ginger.
Thinly slice the pork.
Heat the sesame seed oil in a pot. Spread the pork slices and cook, stirring occasionally, until lightly browned.
Add the ginger and onion slices to the pork; continue cooking with occasional stirring until the onion slices are soft.
Pour the dashi into the pot.
Simmer the pork for about 20 minutes or until tender.
Drain the now-swollen wood ears and cut into bite-size pieces.
Add the wood ears, carrot and beans to the pork. Cover the pot and simmer until the vegetables are done.
Place the miso paste in a bowl and add a cup of the hot broth. Stir until no lumps remain.
Pour the diluted miso paste into the pot and stir. Taste. Add more salt, if needed.
Serve thr pork and vegetables miso soup topped with sliced scallions.