Scrape the skin off the burdock root with the back of a knife, slice diagonally, then cut into thin strips. Soak in water. Cut the carrot into thin strips. Trim the roots off the kaiware sprouts and cut them in half.

Make a slit in the mentaiko and extract the contents.

Boil water in a pot, add burdock root and carrot, and cook for 3–4 minutes. Drain and let cool slightly.