Heat dashi stock in a pot until it comes to a gentle simmer.
Soak wakame in cold water for 5 minutes, then drain and add to the pot.
Add cubed tofu to the pot and simmer for 5 minutes.
In a separate bowl, dissolve miso paste in a little cold water, then add to the pot.
Stir gently and heat the soup just until hot, but do not boil.
Turn off the heat, add green onions, and serve immediately.
Notes
Add miso paste at the end to preserve its flavor.
• Avoid boiling the soup after adding miso to prevent flavor loss.
• Use cold water to dissolve miso paste before adding it to the soup.
• Soak dried wakame in water before using to rehydrate it.
• Adjust the amount of miso paste according to your taste preference.