I keep meaning to have a go at mastering the art of making sushi rolls (without any dead fishies, obviously), but I haven't got around to it yet.
My childhood was filled with homemade rolls (can't really even call it sushi at this point) that tended to disappear rather quickly.
We'd use the basic nori sheets you can buy at any self-important hippie grocer (also good for just snacking on straight, especially fun if you try to talk while the ultra-dry seaweed clings to the inside of your mouth), cook up some rice (actually tended to use brown rice rather than polished, although I forget which strains offhand) and chill it, then add some thin slices of carrot and cucumber along with the secret ingredient... Umeboshi plum paste.
Umeboshi plum paste is this partially-fermented, ultra-tart, midnight purple smear that looks and sounds absolutely horrific but is really quite tasty. Also something-something digestive aid/stomach calming, but that's all hearsay as with most such claims.
It's also bizarrely good on corn cobs instead of butter. The contrast of sweet and tangy is quite nice. Use in moderation though, the stuff's really potent and just a dash will give lots of flavor.
I'm almost certain you can get it at a temple of morality like Whole Foods, and if not there's sure to be some other specialty shop of culinary weeabooism around.
I had a very... Nonstandard diet growing up.