Fill a saucepan with water and bring to the boil. Add a pinch of salt, then add the spinach, stems first. Cook for 1-2 minutes, then rinse with cold water and drain.
Squeeze out the excess water, cut into 3-4 cm long sections, then squeeze again.
Put the spinach in 2 small bowls, garnish with katsuobushi and drizzle the dashi shoyu over it.