Pu Erh is the only tea that is deliberately fermented. Where every other leaf is dried and oxidised and then left alone, Pu Erh is piled, kept warm and humid, and turned over weeks while microbial cultures work through it. Time does the rest. The result is a tea with no sharpness in it at all — dark, round, faintly sweet, closer to cocoa or damp forest floor than to anything else that comes out of a teapot.

It is also the one tea that improves with keeping. Traditionally it was pressed into discs and cakes and carried by mule along the old trade routes into Tibet, ageing on the road as it travelled. Good Pu Erh is still valued by its year.

The spice here is the northern European winter rather than the Chinese one: cinnamon bark and whole cloves, cardamom pods, dried apple and orange peel, hazelnut and walnut. Against a lighter tea this would flatten everything underneath it. Pu Erh has the depth to carry it, which is why the cup tastes of both at once.