Miso is a salty paste made from fermented rice or soybeans and is traditional in Japanese cooking. It gives a rich and sumptuous flavor to this spicy broth. Kaffir lime leaves give an aromatic lime flavor; you can find them in Asian groceries. Poaching is a lovely, delicate way of cooking salmon. Keep the skin on to keep it from breaking up as the stock gently simmers.
Place the miso paste in a pan and whisk in the stock. Taste and add a little salt if necessary. Bring to a simmer (don’t boil too rapidly, or it may separate), then add the lime leaves, chiles, and ginger.
Cut the salmon in half widthwise, then add to the stock, skin side down, and gently simmer for 8–10 minutes, basting the salmon in the liquid until cooked through.
Separate the bok choy leaves from the stems. Chop the stems into bite-sized pieces and shred the leaves. Slice the broccoli into bite-sized pieces.
Carefully transfer the salmon to a plate with a fish spatula and pour a small ladleful of broth over it. Bring the stock remaining in the pan back to a boil.
Put the broccoli into the broth to cook, and after 30 seconds add the bok choy stems. Cook for an additional 1–2 minutes, then add the shredded bok choy leaves. Cook for about 1 minute until wilted. Meanwhile, flake the cooked salmon into large chunks, discarding the skin.
Just before serving, add half the mushrooms to the broth. Rub your serving bowls with a little toasted sesame oil, then divide the remaining mushrooms among them. Add some flaked salmon and vegetables to each bowl, then spoon over some broth. Serve immediately, garnished with cilantro if you like.
HOW TO COOK FIBROUS GREENS
With vegetables such as bok choy and Swiss chard, which have quite fibrous stalks, it is often best to remove the leaves and add them a few minutes later, or else they will be overcooked by the time the stalks are tender.