Combine the broth, sake or rice wine, soy sauce, oyster sauce, cornstarch and sugar in small bowl, set aside.
Heat a nonstick wok or large deep skillet over medium-high heat until a drop of water sizzles. Swirl in the oil, then add the garlic. Stir-fry until fragrant, about 10 seconds. Add the broccoli and stir-fry until crisp-tender, about 3 minutes. Add the broth mixture and cook, stirring constantly, until the mixture thickens, about 1 minute.
Stacy's Notes: This is really good! Don't steam the broccoli first, Tim likes it better a little crisper. I haven't ever used the oyster sauce since I don't have that on hand, and I use cooking sherry for the sake, but it still comes out really good. A definite keeper!