Heat the dried kelp over a gas flame or under a broiler (grill), then put into a bowl with all other ingredients. Refrigerate for 3 days, then strain. Can be stored for up to 1 year. (Bottled ponzu can be purchased in Japanese stores.)
Tags: Japanese
Source: http://www.bento.com/trt-basics.html Reprinted from the book: The Food of Japan by Takayuki Kosaki and Walter Wagner