Peel the satoimo, cut into bite-sized pieces, and rub with 1 tsp salt (not listed in ingredients). Rinse under running water to remove the sliminess. Rinse the nameko mushrooms briefly in water and drain.

In a pot, add water and dashi powder. Heat over medium heat until boiling, then add satoimo. Cover and simmer over low heat for about 7 minutes until tender.

Add the nameko mushrooms and bring to a boil. Dissolve miso paste into the soup and warm through.