Sushi in early times was fast food. It was food you could buy on the street and eat in your hand while on the run.
There is a method to preserve fish that involves cooked rice mixed with salt. Fish are cleaned, stuffed with the rice mixture and put into a barrel where more rice is added over the fish. More fish is added with more rice until the barrel is full. The barrel lid is put in place and held down by two 100 pound rocks.
Then the fish and rice ferments.
For 12-15 months or so...
The rocks hold the lid in place when the barrel gasses.
Some times the barrel produces enough gasses to launch the lid and rocks into the air.
The fermentation produces CO2 gas and lactic acid which helps preserve food. The fish shall we say has an aroma that drives off even Japanese.
But it is also considered a delicacy.
There is a Bizarre Foods episode where they go to a place that makes this product. The traditional methods of production are going away in Japan.
So what the heck does this have to do with Sushi?
Since Rice historically has been a very expensive food throwing away the rice used to preserve the fish was wasteful. A method of fish preservation that took less time was created. With this method the rice can still be eaten.
Eventually an even faster method of preservation was created that used sake, rice wine and rice vineger. Sound familiar?
The fish preserved 12-15 months is called funa-zushi.
Fish preserved in a shorter amount of time is called nama nare-zushi.
The sake, rice wine and rice vinegar preservation method is called haye-zushi.
Eventually a pressed product called oshi-zushi was created where the rice was pressed into a shape. This was followed by hako-zushi which is boxed sushi where the rice was into a mold and fish was put on top. The mold top was pressed down to firm up the food which was then cut into bite sized pieces. Eventually other foods besides fish where put into the mold.
This pressed mold method eventually morphed into nigiri zushi of today. Nigiri was even quicker to produce but it was much larger than what we have today. The rice shortage after WWII forced a change in sushi. With rationed rice brought in by the customer, one cup of rice could make 10 pieces of sushi, seven nigiri and three pieces of roll.
Todays sushi was based on rice used to preserve fish through pickling/fermentation. The rice was then used to make a fast food product on the streets of Japan.
Whether you wish to think about this or have it as a topic of conversation while eating sushi I will leave to the reader/diner.
Fermented fish does not sounds good but I would try it if it was prepared the traditional way. Might help to have a sinus infection though.
Later,
Dan