@KthulhuKat
The pu-er process is also cool in that all the work is done by mold. They wet the leaves after initial processing (to turn it into green tea or black tea or oolong), blow mold spores over the wet leaves, let the mold grow for weeks -> months.
The mold eats the bittering agents but not the other flavors. They dry it, the mold turns to spores. They blow air over it to remove the spores & voila!
You can also tell your friends you paid extra for the mold :)