Tea
/Pu'er is actually a different plant then all the other things we call tea, but it has simular effects.
When I have more time I've got some things to say about tea, but not today. I was totally deep into Chinese tea for about ten years. Then I just quit because it seemed like I was accumulating too much stuff.
When I went backpacking or mountaineering or rock climbing I would bring all these little cups and a pot or brewing device. So refined.
Then I discovered instant coffee. Wow, so cool, so convenient, and what great flavor!