Exactly which kind of cardamom should I use in pho (phở)?
In phở soup, we use thảo quả, or Lanxangia tsao-ko, formerly known as Amomum tsaoko. Thảo quả trees are grown in Northern Vietnam, Laos, and in Yunnam China (known as 草果).
We call Black cardamom (Amomum subulatum) as đậu khấu thơm. Black cardamom trees are grown in India, Nepal, Burma, Tibet, Yunnam. Black cardamom trees are not native to Vietnam, and their pods are not used in phở traditonally.
We call green cardamom (Elettaria cardamomum) as bạch đậu khấu. Like black cardamom, it's not used in phở, either.