Place 6 cups of water in a medium pot. Place the kombu and the dried shitakes in the pot and let soak for 30 minutes to 1 hour (longer if you have time).
If using wakame, soak in a small bowl of water for about 5 minutes to rehydrate. Drain and set aside.
Remove the shitake from the pot and set aside. Bring the water to a rapid simmer. Thinly slice the shitake.
Once the water (or now our dashi) is just about to boil, reduce to a simmer and remove the kombu and discard or compost (or reuse in another recipe). Add the sliced shitake, onion, carrot, sliced bok choy stems (not the leaves), and the cubed tofu to the pot. If you like a lot of tofu in your miso soup (as we do) add the full block. If this is your first time making miso soup, start with half a block or you can omit the tofu altogether for a lighter version.
Simmer the veggies and tofu for 8 minutes or until very tender then turn the heat off and stir in the bok choy leaves and rehydrated wakame.
Remove about ½ cup of the broth from the pot and place in a bowl with the miso. Mix together until the miso dissolves and a loose paste forms. Stir the miso back into the pot. The soup should turn cloudy and no chunks of miso visible.
Ladle the miso soup into bowls and top with sliced scallions. Add a drop or two of tamari or soy sauce to season.