I actually did a ton of research about the different components GF Irish foods, so it was my turn to answer you in way too much detail, over at my blog!

I’ve never seen anyone use sushi-vinegared rice for onigiri in Japan, actually… Onigiri tends not to be made from sushi-seasoned rice or anything so fancy- It’s a quick lunchbox item made from fresh, hot rice and gets its flavoring from the filling and maybe salt and sesame seeds to the rice. Moms literally take the rice fresh from the rice cooker and mold it, often in plastic wrap. It’s all about the fresh, warm rice and how it goes together with the filling.

Here’s a pretty traditional (and yummy take) on onigiri.
http://www.justhungry.com/2003/12/obento.html
(many of her fillings are not vegetarian)

I love the taste of good rice- the sushi-type rice happens to be what is standard in Japan (short, fat grains of starchy rice) and preferred, and I don’t find it bland at all. However I do enjoy the pow added by sesame seeds and a little salt.

You would pretty much only use vinegared rice for maki sushi or nigiri-zushi (not the same as Onigiri)… I suppose also for chirashi zushi (rice with assorted toppings sprinkled) and inari zushi (fried tofu pouches stuffed with rice).

http://en.wikipedia.org/wiki/Sushi

Here’s Maki’s very good explanation of the difference between sushi and onigiri:

“Again it’s a matter of how things are normally categorized in Japanese cooking, but generally speaking anything made with vinegar flavored rice, or sushi rice (sushi meshi or shari) is sushi. So you could make an onigiri-shaped item with shari, and call it an onigiri, but if a Japanese person ate it s/he would probably think it’s sushi in an onigiri shape.” -Maki from http://justbento.com/handbook/bento-basics/onigiri-omusubi-faq

I hope this helps! Really interesting question. I lived in Japan for several years and often spend time during the summer there so am pretty familiar with Japanese cooking. My take on onigiri tends to be very “fusion” oriented, though, partially because I think it is fun to play with my food. :)

-Sea

Duck and I just discovered Daiso (we’ve been there twice already in a week and ahalf!) and it looks like we’ll be making another trip back out there for onigiri molds!

I notice from the recipes that you don’t season your sushi rice. It’s not too bland with the plain rice? That would certainly be a time-saver.