Sōmen (素麺) are very thin, white Japanese noodles made of wheat flour. The noodles are usually served cold and are less than 1.3 mm in diameter. The distinction between sōmen and the next thicker wheat noodles hiyamugi (冷麦), and even thicker Japanese wheat noodles udon (饂飩) is that sōmen is stretched while hiyamugi and udon are cut.

Summer-style cold somen

Sōmen are usually served cold with a light flavored dipping sauce or tsuyu. The tsuyu is usually a katsuobushi-based (鰹節/dried bonito shavings) sauce that can be flavored with chopped thin leeks, ginger, or myoga. In the summer, sōmen chilled with ice is a popular meal to help stay cool.

Somen Meal Sample

Fish stock can easily be replaced with konu/seaweed stock if you vegetarian or vegan.

Nagashi Somen flowing down a bamboo pipe.

Some restaurants offer “nagashi sōmen” (流しそうめん flowing noodles) in the summer. The noodles are placed in a long flume of bamboo across the length of the restaurant. The flume carries clear, ice-cold water. As the sōmen pass by, diners pluck them out with their chopsticks and dip them in tsuyu. Catching the noodles requires a fair amount of dexterity, but the noodles that aren’t caught by the time they get to the end usually aren’t eaten, so diners are pressured to catch as much as they can. A few luxurious establishments put their sōmen in real streams so that diners can enjoy their meal in a beautiful garden setting.

Nyumen

Sōmen served in hot soup is usually called “nyumen” and eaten in the winter, much like soba or udon are.

Somen champuru.

In Okinawa, somen champuru are very popular with goya and tofu.

Plain somen

Somen are probably the easiest style of noodles to prepare.
Plain chilled somen witj cold ponzu are such a great snack in summer.

A very similar variety of thin wheat flour noodles are called somyeon in Korea and are used in a dish called bibim guksu.