star anise
The dried, star-shaped fruit of an evergreen tree from southern China, with a strong, sweetish anise aroma.
Caution: True Chinese star anise is safe, but the similar-looking Japanese star anise is toxic, so use only star anise sold as food and not decorative or unlabelled pods.
Star anise is stocked in the spice aisle of many supermarkets, especially around winter, but not everywhere all year round. Asian grocers reliably carry it, often cheaper and in larger packs.
Substitute:
Aniseed or fennel seed gives a similar anise note but is milder and less warm; use about half a teaspoon per star. The deep, slightly woody depth of star anise will be missing.