Gai Lan or Chinese broccoli is a common (and probably the only greens) vegetable dish you see on a trolley at dim sum restaurants. It is usually served with oyster sauce because the sweetness of the sauce complements the slight bitter taste of the leaves. This is a very easy dish to prepare. Although the stem of this vegetable is thick, it doesn’t take much time to cook. The key is to cook the leaves separately from the stems in boiling water.