Everything you want (need) to know about miso but were afraid to ask.

http://www.seriouseats.com/recipes/2008/09/miso-soup-recipe-trevor-corson.html
check out Trevor Corson's explanation and photos.

Actually, if you have not read his book on Sushi, it give you a really authentic background on where sushi and so many other foods that you have probably seen, comes from. There is such basic explanation of why fast-twitch and slow-twitch muscles taste different. Fast twitch of course is anaerobic (just like sprinters) and slow twitch have to be aerobic (like distance runners). They have different nutritional and resource needs / expenditures, and of course they taste different.

http://www.trevorcorson.com/sushi/book.html - check it out. I have not read his "secret life of lobsters" (yet), just have not quite got around to it.
http://www.youtube.com/watch?v=Wy_0z2rdRRo