Zaru Soba is a Japanese noodle dish consisting of buckwheat soba noodles served cold with an arrangement of side garnishes.
The soba noodles are boiled for 7 to 8 minutes, then rinsed in cold water, drained, chilled, and spread out on a flat serving dish such as a wicker plate, bamboo tray or sieve (called a "siero.")
Beside the plate accompanying the noodles are sliced cucumber, tomatoes, chopped green onion, possibly some sliced pork, and possibly some flaked nori. In the Nagoya area of Japan, people like to add mayonnaise as well.
They will be served with either a side dipping sauce made from soy sauce and vinegar, perhaps with a bit of wasabi and a sprinkle of chopped green onion stirred in, or with a cold broth made perhaps from dashi, soy sauce and mirin.
At the end of the meal, you can add some of the water used for boiling the soba noodle in (called "soba yu") to the leftover dipping sauce, and drink it.
Zaru Soba is a classic summer dish, but it is also traditional on New Year's Eve.