Cut spinach into 4 cm lengths.

Reconstitute the freeze-dried tofu in water or lukewarm water.

Cut the reconstituted tofu into 8 equal parts.

Combine dashi stock, sugar, mirin, and usukuchi soy sauce in a pot.

Bring the mixture to a boil.

Add the tofu to the boiling broth.

Cover the pot with a lid slightly opened.

Simmer over low to medium heat for 7 to 8 minutes.

Remove the lid and add the spinach.

Cook until the spinach becomes tender, about 5 more minutes.

Serve hot.