Wash and dry the bok choy leaves.
Heat the vegetable oil in a wok or large skillet over medium high heat. Add the garlic and ginger and sauté, constantly stirring to ensure they do not burn. Add the mushrooms and fry for about a minute. Add the greens and sauté, adding the sesame oil, rice wine vinegar, soy sauce and pinch of sugar. Cook for another couple minutes, just until the bok choy has begun to wilt. Enjoy while warm.
If you can’t find fresh shiitake mushrooms, dried ones work equally well. Use 2 to 4 ounces dried mushrooms. Place the dried mushrooms in a large bowl and cover with boiling water. Let sit for about 20 minutes. Remove from the water, squeezing the excess water out of the mushrooms. Cut off the stems and use the caps as directed in the recipe. The remaining soaking liquid is delicious used as a base for soup or a stock.