Cao guo is a variety of black cardamom grown in China, used to impart big, smoky flavours to slow-cooked dishes. While green cardamom is known for its delicate, almost sweet flavours – both black cardamom and Chinese cao guo are savoury spices, with their strong flavours best suited to slow cooking.
Cao guo comes from the same family as black cardamom – indeed, both are related to ginger. In the autumn, when the pods open, cao guo is hand-harvested, sun-dried and crushed, so the seeds are released from the pods. Committed cooks can grind down a cao guo pod, and season dishes with a light sprinkle of the powder. Most often though, a whole cao guo pod is added to red-braised and slow-cooked dishes to release its savoury-smoky flavours over time. For the easiest way to get to grip with cao guo’s flavours, add a pod to plain rice cooking in a steamer, so that its enjoyably bitter, smoky notes infuse through the dish.