The “grain” in 45 grain brown rice vinegar

I have never made, but I have eaten Arborio sushi, with Italian flavors and here in DC I have had latin-flavored sushi. It was all great. The Arborio sushi seemed like plain Arborio rice to me.

The rice vinegar is sweet and less acid (4% versus 6%), so if you try different vinegars you may want to dilute it a bit first and then compare for sweetness. Say you have 2 tablespoons of vinegar at 6%, then add add one tablespoon of water to it to bring it down to 4%.

I would probably use diluted white cranberry juice, as being the flavour closest to rice wine vinegar. I am not sure if the acidity would be sufficient, however; you may need to add lemon juice. A substitute for soy you will not easily find, as the development of those sorts of flavours requires fermentation.