Step 1

Soak 14 dried shiitake mushrooms in room temperature water overnight. Remove the mushrooms from the water and squeeze the excess liquid out. Trim off the stems; set aside.

Step 2

Place the broth, oyster sauce, tamari or soy sauce, sugar, sesame oil, and rice cooking wine or sherry in a medium bowl and stir to combine; set aside.

Step 3

Heat the oil over high heat in a wok or large skillet until shimmering. Add the garlic and ginger and stir-fry until fragrant, about 30 seconds. Add the mushrooms and stir-fry for 1 minute. Add the chicken broth mixture and bring to a boil.

Step 4

Reduce the heat to medium-low. Cover and simmer, flipping the mushrooms every 15 minutes, until the mushrooms are tender, 30 to 45 minutes total. About 15 minutes before the mushrooms are ready, prepare the bok choy.

Step 5

Bring a large pot of water to a boil over high heat. Meanwhile, cut each head of bok choy in half through the stem to keep the leaves together. Wash and drain well. Prepare a large bowl of ice water; set aside.

Step 6

When the water is boiling, add the bok choy and blanch until crisp-tender, about 2 minutes. Drain in a colander, and then transfer the bok choy immediately to the ice water bath. Let sit for 1 minute, then transfer back to the colander and drain well. Transfer the bok choy to a round serving plate, arranging them cut-side down in a single layer with the leaves pointed toward the center; set aside.

Step 7

When the mushrooms are ready, place the cornstarch and 2 tablespoons water in a small bowl and stir until the cornstarch is fully dissolved. Add to the mushrooms and cook uncovered until the sauce is thickened, 1 to 2 minutes. Arrange the mushrooms over the bok choy and pour the sauce over the mushrooms.