To make dashi: In a measuring cup (or a large pot), add 4 cups water and kombu and let it steep. You can do this process overnight or as soon as you start preparing. This is kombu dashi. If you're using dashi powder or dashi packet, follow this tutorial, and use it at Step 12.
Transfer the kombu dashi into a pot (if you didn’t use a pot at Step 2). Slowly bring the kombu dashi to a boil over medium low heat. When the water is almost boiling, remove the kombu to avoid sliminess. If you are vegan/vegetarian, skip next two steps (Step 9 and Step 10).
Bring the soup mixture to a boil, skimming the foam and scum on the surface while cooking. Turn off the heat and add 2 Tbsp miso first, and then gradually add in more as you taste the soup. Each miso brand and type of miso tastes differently and the sodium level varies, so you want to taste before adding more miso.
Add the tofu into the soup and turn on the heat to continue to simmer until tofu is nice and warm (tofu is edible chilled, so you don’t have to worry about “cooking” it). Just make sure not to let the miso soup boil. It should take not more than 3-4 minutes to warm the tofu, and the soup is now ready.
Recipe by Namiko Chen of Just One Cookbook. Please do not copy this recipe and images without my permission. If you want to share this recipe on your site, please re-write the recipe and link to this post as the original source.