Bring the water to a boil. Pour the hot water into a bowl with the dried shiitake mushrooms. Set aside to let the mushrooms hydrate for about 20 minutes. Save the soaking liquid. Trim and discard the mushroom's tough stems. Slice the mushrooms into 1/8-inch strips.

In a medium soup pot, simmer the chicken broth with the mushroom soaking liquid (be careful not to add any grit or sand that may be at the bottom of the mushroom broth). Add half the ginger slices and all the scallions to the broth and simmer for 10 minutes.

Heat the oil in a large skillet or wok. Stir-fry the bok choy over high heat for 3 minutes, or until crisp-tender. Season the bok choy with the salt and pepper. Add the bok choy, mushrooms, and bean curd to the broth, and continue to simmer for 5 minutes.

Serve the soup in bowls with the remaining ginger sprinkled on top.

This recipe yields 4 servings.