is a type of thin Japanese noodle made from buckwheat flour. It is served either chilled with a dipping sauce, or in hot broth as a noodle soup. Moreover, it is not uncommon in Japan to refer to any thin noodle as soba in contrast to udon which are thick noodles made from wheat.
In Japan, soba noodles are served in a variety of situations. They are a popular inexpensive fast food at train stations throughout Japan, they are served by exclusive and expensive specialty restaurants, and they are also made at home. Markets sell dried noodles and men-tsuyu, or instant noodle broth, to make home preparation easy.
Some establishments, especially cheaper and more casual ones, may serve both soba and udon (thick wheat noodles) as they are often served in a similar manner. However, soba is traditionally the noodle of choice for Tokyoites. This tradition originates from the Edo period when the population of Edo (Tokyo), being considerably wealthier than the rural poor, were more susceptible to beri beri due to their high consumption of white rice which is low in thiamine, and are thought to have made up for this by regularly eating thiamine-rich soba. Every neighbourhood had one or two soba establishments, many also serving sake, which functioned much like modern cafes where locals would drop by casually.
Soba is typically eaten with chopsticks, and in Japan, it is traditionally considered polite to slurp the noodles noisily. This is especially common with hot noodles, as drawing up the noodles quickly into the mouth acts to cool them down. However, quiet consumption of noodles is no longer uncommon.
Cold Chilled soba is often served on a sieve-like bamboo tray called a zaru, sometimes garnished with bits of dried nori seaweed, with a dipping sauce known as soba tsuyu on the side. The tsuyu is made of a strong mixture of dashi, sweetened soy sauce (also called "kaeshi") and mirin. Using chopsticks, the diner picks up a small amount of soba from the tray and swirls it in the cold tsuyu before eating it. Wasabi, scallions, and grated ginger are often mixed into the tsuyu. It's said that the best way to experience the unique texture of hand-made soba noodles is to eat them cold, since letting them soak in hot broth changes their consistency. After the noodles are eaten, many people enjoy drinking the water in which the noodles were cooked (sobayu), mixed with the leftover tsuyu.
Hot Soba is also often served as a noodle soup in a bowl of hot tsuyu. The hot tsuyu in this instance is thinner than that used as a dipping sauce for chilled soba. Popular garnishes are sliced scallion and shichimi togarashi (mixed chilli powder).
The most famous Japanese soba noodles come from Nagano. Soba from Nagano is called Shinano Soba or Shinshu soba. Ni-hachi (二八, two-eight) soba, consists of two parts of wheat and eight of buckwheat; Juuwari (十割, 100%) soba, the finest (and usually most expensive) variety, consists entirely of buckwheat.
Soba is also the Japanese word for buckwheat. Roasted buckwheat kernels may be made into a grain tea called sobacha, which may be served hot or cold. Buckwheat hulls, or sobakawa(also called sobagara), are used to fill pillows. Sometimes, beers are made with roasted buckwheat added as a flavoring, and called "soba ale"
Soba is occasionally used to refer to noodles in general. In Japan, ramen is sometimes called chūka soba or shina soba (both mean Chinese noodles). Parboiled chūka soba is stir-fried to make yakisoba. Note that these noodles do not contain buckwheat.
In Okinawa, soba usually refers to Okinawa soba, a completely different dish of noodles made out of flour, not buckwheat. Okinawa soba is also quite popular in the city of Campo Grande (Brazil), due to influence of Japanese (Okinawan) immigrants. It is eaten at street markets or in special restaurants called "sobarias".