Pour the vegetable broth into a large saucepan, then add the sliced carrot, mushrooms, and grated ginger.
Bring the broth to a gentle simmer and cook for about 5 minutes until the vegetables begin to soften.
Add the tofu cubes and continue simmering gently for another 3 minutes.
Stir in the spinach and half of the sliced green onions, cooking just until the leaves wilt.
Place the miso paste in a small bowl, add about ½ cup of warm broth, and whisk until completely smooth.
Remove the saucepan from direct heat, then stir in the miso mixture, sesame oil, and soy sauce.
Divide the soup among bowls, garnish with the remaining green onions, and serve without boiling again.
