Pu erh is the only truly fermented tea. Raw pu erh begins as a special type of green tea, it is then pressed into cakes and left to mature. The ageing process is done in high humidity, allowing micro-organisms naturally within the tea leaf to develop and do their magic, they transform bitter astringency into smooth, complex, earthy flavours and aromas. Pu erh is said to be one of the healthiest teas, excellent for digestion and reducing cholesterol.