Blanch the spinach in boiling water for 1 minute then refresh in cold water. Drain very well.
Using a mortar and pestle, grind 3 tbsp toasted sesame seeds. Add sugar and continue to grind until a paste starts to form. Mix through 2 tbsp soy sauce and check the seasoning.
Dress spinach with the sesame and soy sauce and arrange across the bottom of a shared serving dish.
Gently remove the tofu from its packet. For perfect presentation, trim the edges carefully before cutting into four slices. Place the tofu slices on top of the spinach.
Using a microplane, grate ginger evenly over the tofu and splash over the remaining soy sauce. Garnish with the shredded nori, spring onions and remaining toasted sesame seeds.