Tips for cooking Sushi Rice
Good Sushi Rice has several contradicting qualities, which make it difficult to cook:
It has to be (very) sticky. (Otherwise you won't be able to produce Nigiri Sushi).
It mustn't be too soft. (We don't want rice mush. The single rice corns should be identifiable.)
It mustn't be too hard. (We dont't want to hear or feel a "Crunch" while eating.)
After several not very successful attempts to cook good Sushi Rice I finally found a way to get a decent result without spending too much time. (A sushi master probably won't find it adequate :-)).:
Use short grained sushi rice. (Long grained rice won't work, because it doesn't get sticky enough.)
Wash the rice until the washing water starts to get clean. (You can wash the rice in a sifter or in a big pot. If you use a big pot, you have to pour off the water several times; if the pot is big enough this can be done easily without spilling rice. Most people recommend that you drain the rice for one hour... but it seems that this it not very important for the final result.)
To cook the rice use about 15% more water than sushi rice measured in volume. (So if you use 1 cup of sushi rice, use a little bit more than 1 cup of water.)
Bring the water to boiling point without the rice. (You can add some salt if you want - this depends on your personal taste.)
Put the rice into the boiling water and continue to boil on the highest heat level of your oven. To prevent the rice from sticking to the bottom of your pot, stir the rice several times while it boils. (This is important! Otherwise a thick layer of rice will stick at the bottom of your pot.)
After 2-3 minutes turn the heat down to lowest level. (The water should barely continue to boil. If you have an electrical oven, you can put the pot away from the heat until the plate gets colder.)
Put a lid on the pot and let the rice simmer for about 10-15 Minutes. (There mustn't be to much heat! Otherwise the lowest layer of rice will stick to the bottom of the pot.)
As soon as the rice has absorbed the water, put it away from the oven and let it rest within the pot covered by the lid. Wait for about 15-20 minutes. (This also seems important! If you don't wait, your rice probably will be too crunchy.) After that you can add sushi vinegar (see below) and stir the rice.
Usually you put the rice in a special wood bowl and mix it there with the vinegar, to avoid chemical reactions with your metal pot. Another solution is to put the rice into a ceramic baking pan.
Spread the rice in the baking pan (or somewhere else) so that the rice cools down quickly. Cover the tray with a towel to prevent the rice from drying out. (Sushi rice should be used when it is cold. If you are working under time pressure warm rice will also work.)
That's it :-)
In my experience the two most important points are the boiling time at full heat and that you let the rice rest after it simmered: If you boil the rice too short it won't get soft, if you boil it too long it will get too soft or it will burn. 2-3 minutes seems to be the right time, but it might vary with different rice brands. Let the rice rest for at least 15 minutes. The last time I didn't let it rest, the rice was very soft (mushy) on the outside and still crunchy at the core...
One middle sized cup of rice (approx. 0.2 litre) seems to be enough for 4 rolls of maki sushi, if the rice is spread thin on the nori mats. Four rolls of maki sushi usually is enough for a meal.
Sushi vinegar is made by mixing rice vinegar with sugar. The amount of sugar and vinegar depends very much on the personal taste. Some people use a 1:1 ratio between sugar and vinegar (which is too sweet in my opinion) others a 1:3 ratio (1 part sugar 3 parts vinegar). Some people add salt (which can also be added to the cooking water directly). Approximately 5 tablespoons of rice vinegar are used for 1 Kg rice, but of course this also depends on your taste.