Prepare the dashi: Combine kombu and water in a pot. Bring to a simmer, then remove the kombu. Add the katsuobushi and simmer for a few minutes. Strain the dashi.
In a pot, combine the prepared dashi and miso paste. Stir until the miso is dissolved.
Add the shiitake and enoki/shimeji mushrooms to the pot and simmer until softened.
Add the bok choy and tofu. Simmer for a few more minutes until the bok choy is tender.
Garnish with sliced spring onion and serve immediately.