Chirashi is the most common form of sushi eaten at home in Japan. A lacquered container is filled with su-meshi, and various colourful toppings are arranged on top.
Slice the tuna across the grain into 7.5 x 4cm/3 x 1½in pieces, 5mm/¼in thick, using a very sharp knife. Slice the squid crossways into 5mm/¼in strips. Place both on a tray, cover with clear film (plastic wrap) and chill.
Remove and discard the stalks from the shiitake. Pour the soaking water into a pan, add the shiitake and bring to the boil. Skim the surface