Place in a small heatproof bowl:
Pour over the mushrooms:
Let soak for 20 minutes, stirring occasionally. Lift the mushrooms from the bowl, reserving the soaking liquid. Cut the mushrooms into ¼-inch-thick slices. Strain the soaking liquid and transfer 2 tablespoons to a small bowl. Stir in:
Combine in another small bowl:
Heat in a wok or a large skillet over high heat:
Add the sliced reconstituted mushrooms and:
Stir-fry until the bok choy is starting to wilt, 3 to 4 minutes. Add the chicken broth mixture, cover, and steam until crisp-tender, 1 to 2 minutes. Stir the cornstarch mixture, add to the pan, and bring to a boil, stirring. Add:
Stir well and serve immediately.