Seen here is a quantity of special magic sushi vinegar. This gets added to the rice when it's done cooking, to give it a sorta sweet sorta sour sushi-rice like taste. There's three tablespoons of it in there, one for each cup of rice that we cooked up.
I bought actual sushi vinegar, so I just poured it directly from the bottle into the measuring cup for inclusion in the rice. It's a combination of rice vinegar, a bit of sugar, and a bit of salt though. For actual proportions, consult a recipe, you lazy bastard!
SushiChef was nonplussed by my inclusion of authentic sushi vinegar in the sushi proceedings, as he favours a magic powder you can buy in packets and add to the rice instead, which gives it a flavour but is less work or something.