Just Bento has a good recipe for shio konbu on her site. Try this. Be sure you are using konbu and not nori…just thinking about you mentioning “shredded konbu”. But I’m sure you know what you are talking about:) Good luck!

Two common filllings that you would have to get at a Japanese food supplier would be umeboshi or konbu, which is seasoned seaweed. But you occasionally also find takana as a filling, particularly in Western Japan. You can make this yourself by stir-frying a few leaves of mustard greens with a tiny bit of salt or soy sauce and the stirring in some sesame seeds. Be sure to squeeze out all the water before you add the sesame seeds because you don’t want soggy onigiri:) Common non-veggie fillings would be salmon or tuna mayonaise as well as mentaiko or tarako (spicy and non-spicy pollack roe) and sometimes even chicken. Happy onigiri making!