Put the water into a medium sauce pan over medium heat. Bring it to a boil. Add the dashi packet to the water and let boil for about 10 min (or if you can read the instructions on the dashi packet box, follow those directions to make the dashi).
While dashi is cooking, put the dried wakame in a about ¼ cup of water to re-hydrate for about 5 minutes. When re-hydrated, drain and squeeze out any excess liquid. If the wakame pieces are pretty big, cut up into bite-sized pieces.
Split up green onion and wakame evenly between 3-4 bowls.
When dashi is finish, discard the dashi packet. Turn down the heat so dashi stock is at a simmer. Place miso paste into a strainer, and dip the strainer into the dashi stock to dissolve the miso into the dashi. Use a spoon to press the miso through the strainer. The dashi will get cloudy and there will be tiny white bits left in the strainer. Discard the little white bits.
Add the tofu cubes to the dashi/miso mixture. Gently stir and cook for about a minute, or enough to heat the tofu up. Keep mixture warm, but not boiling so you don't break up the tofu. When ready to eat, pour hot dashi mixture with the tofu into each of the bowls you had prepared with green onions and wakame. Serve hot and enjoy!
Recipe by Learn by Cooking at https://www.learnbycooking.com/miso-soup/