Wipe out the wok. Add the oil, and when it begins to smoke, add the dried chiles, fermented black beans, ginger and garlic and stir-fry until fragrant, about 20 seconds. Add the onion and mushrooms and stir-fry until just beginning to brown, about 2 minutes. Add the blanched vegetables and cook for 1 minute, then add the soy sauce, vinegar and sugar and stir-fry for 30 seconds. Add the broth and bring to a boil. Add the cornstarch mixture and cook, stirring, until the sauce thickens, about 15 seconds. Swirl the sesame oil over the vegetables and serve.