Natto (なっとう or 納豆) is produced by steaming soybeans and adding the bacteria called natto-kin (納豆菌) in Japanese (Bacillus subtilis natto) to enhance fermentation.
Due to the fermentation, the soybeans become sticky, smelly and rather slimy. Like some strong cheeses such as blue cheese, natto is definitely an acquired taste, even in Japan. If you can overcome the sticky, smelly, slimy aspects, natto is really very good. Its appearance and smell definitely belie its taste. The fermentation creates a rich, nutty flavor that is actually very good.
Natto is a very healthy food. It is a great source of protein and nutrients such as Vitamin K, and the pyrazine enzyme (which is said to help reduce the likelihood of blood clotting) and the nattokinase enzyme (which is said to help dissolve blood clots once they have formed).
Natto is sold in supermarkets all over Japan. The supermarket nearby has 26 different varieties at last count. Natto is usually sold in sets of three or four little styrofoam packets (each pack is about 40-50 grams) . The natto usually comes with a small packet of flavored soy sauce (tare たれ) and hot mustard (karashi からし), as shown in the upper right corner of the photo above.
To prepare natto, empty one pack of natto beans into a small bowl, add the small packets of flavored soy sauce and karashi, and stir everything up. It is important to stir the natto because stirring it increases the stickiness - and that is actually a good thing. The stickiness is caused when natto-kin bacteria breaks down the protein in natto and produces the amino acid called glutamic acid and the saccharide called fructan. The glutamic acid produces umami (うまみ or 旨味), which is said to be the fifth basic taste. Umami is a pleasant savoury taste that is subtle and makes food taste good. Therefore stirring the natto also makes the natto tasty (despite its rather nasty appearance).
There is a bit of debate about how much you should stir the natto but at a minimum the natto should be stirred until it gets sticky and stringy. Stirring it about 10-20 times might be enough, but some people say that if you stir it about 100 times, the amino acid called polyglutamic acid, which is said to be good for health, will increase.
A short video showing how to prepare a pack of natto can be viewed on YouTube at http://www.youtube.com/watch?v=2Ki3X00EcJ0.
Natto is usually served on top of a bowl of hot rice, and it is typically eaten for breakfast.
Some people also add other toppings to the natto such as chopped chives, raw egg (or just a raw egg yolk), dried nori seaweed, sesame seeds, etc.
Now that natto is more popular, it can be found in a lot of other dishes as well. Natto is added to other main dishes for lunch and dinner. Natto can be found as a topping for spaghetti, as an ingredient in sushi rolls, as a filling for omelets, etc.
A short description of my favorite brand of natto is available in the Favorite Stuff Section under the heading Natto.
