Cut salmon steaks into chunks. Halve onion and cut into 0.5 cm
thick slices. Slice potatoes and carrots into 1
cm thick discs (if large, cut into half moons) and parboil
separately. Drain and set aside. Slice shiitake mushrooms diagonally
into 4 slices. Chop coriander leaves or watercress
into 6 cm lengths. Cut tofu and konnyaku, if using, in
half lengthways, then cut tofu into 1 cm squares and konnyaku into
0.5 cm slices. Melt butter in a large cast iron
pot and stir fry onion slices for 1-2 minutes. Add konbu and enough water to
fill half the pot. Bring to the boil over medium heat,
discard konbu and lower heat. Dissolve miso in a bowl with some
of soup, then stir back into pan. Add potatoes, carrots, salmon,
mushrooms and konnyaku, cover and cook over low heat for 5 minutes. Add coriander or watercress and
tofu; simmer for 3-4 minutes. Serve sprinkled with spring onion.
Ishikari is a river on the northern island
of Japan which is famous for salmon.