The best way to know for sure that your miso soup is vegan is to make your own at home. This recipe only has 5 ingredients and can be made in as little as 5 minutes. Who would have thought that homemade miso could be so simple?
The serving size is good for one person but is slightly larger than what you would get in a restaurant. Enjoy by yourself or split with one other person. The recipe can also be doubled or tripled if you're catering for a crowd.
Add the miso paste to the water in a pot and put it on medium heat.
As the water is heating, slice up 1/3 of a block of tofu into cubes and put to the side. Repeat this step for the green onion, cutting them into thin slices.
Use a spoon or a whisk to dissolve the miso paste into the water once it has heated up a bit.
Add the remainder of your ingredients and wait until the seaweed flakes have hydrated and expanded in the soup.
By this time, the soup should be at a low boil and you can remove it from the heat and enjoy.
If you want to make this miso soup more of a complete meal, adding some rice and sesame seeds can be a great way to make it more filling. Obviously, this strays from the more "traditional" recipe, but it's something that I do all the time! You can also add other starches like unseasoned ramen or rice noodles.
Finally, if you want to really up the flavor of this miso, try adding a dash of nutritional yeast or shitake powder for an extra burst of umami.