Chaga (Inonotus obliquus) is a fungus gathered on birch sap. It has been used for centuries for its manu healthy properties : anti-inflammatory, detox, anti-oxydant.
To get the best out of it, simply put 2 or 3 pieces of chaga in a teapot filled with cold water. Let it rest for half an hour, then heat (without boiling it). Sweet it has desired.