The Bamboo Method of Exhalation

I usually use the Bamboo Method of Exhalation when I do sitting or walking zazen. You can read more about it here (page 71). If you're a beginner, then skip about Mu: 'The method is to say, in one breath, with intermittent or wavelike exhalation. We hit upon the name "bamboo method" for this type of exhalation, for just as a bamboo trunk has successive joints or nodes, so exhalation is stopped now... and then for a little while, giving short pauses...' That's all you need to know if you're a beginner.

I usually exhale through pursed lips to create tension in the tanden.