It's brewed not from a leaf but from a fungus — a hard, charcoal-black growth that Siberians chip off living birch trees with an axe.
Chaga tea is steeped from chunks of a dark, woody fungus that grows on birch trees, simmered slowly into a dark, earthy, faintly bitter brew often sweetened with honey. Market stalls and taiga villages across Siberia sell dried chaga chunks by the bag for brewing at home.