Sushi is all about the rice
Many people do not know this but the definition of sushi is 'vinegared' rice Okay, 'vinegared' isn't a real word but if I had just written 'rice with vinegar' that would've sounded like the vinegar was a simple, passive condiment and that wouldn't be anywhere near the truth. Vinegar is the key ingredient to making simple rice into sushi rice.
Since sushi is rice, then what, you may ask, is raw fish? Well, raw fish (that is intended to be eaten raw) is called 'sashimi'' That is why when you go into a market in Japan, you won't find "sushi grade fish" anywhere. That is an American thing (and I am sure common in other English-speaking countries as well). But let's back to the rice.
Sushi rice is made by first cooking rice and then mixing sushi vinegar into the piping hot rice. When you pour a liquid onto hot sticky rice, the rice falls apart and you get a short window of opportunity to mix the vinegar around in a way that it covers every grain. If you wait too long and the rice begins to cool, you will be unable to break the rice apart from its tight, starchy bond.
Aside from simply knowing what the ingredients (rice and sushi vinegar), you also have to have a really good understanding of how to properly cook rice. The rule of thumb for sushi rice is one part dry rice to one part water. Of course, the rice must be washed (and dried) before you put it in the rice cooker with water.
Once it has been washed, dried, cooked, and mixed, be sure to store in an insulated container so it will stay warm when you go to use it. The best sushi is made with warm sushi rice. No exceptions!
The moral of this blog post: If you want great sushi, you better make great rice