I'm going to state the obvious, because it might actually be useful for some.
If you use the search engine for the board (upper right), you must include "and" if you want to search for more than one word.
In other words, if you just type "green sencha" you'll get posts that have either word in them. If you type "green and sencha" you'll only get posts that have *both* words in them.
This isn't obvious unless if you take the time to go to the full search page (upper left, next to FAQ), where it explains this in more detail.
Obvious to some, not to others. Maybe somebody will find it useful, thus I post. (And as you can tell, I was one of the people that just used the shortcut in the upper right, eventually figured out you needed to specify your booleans, and then much later noticed the other search option in the upper left where it verifies this! ).
Edit: because I can't distinguish my right from my left... *sigh*