Hiyashi chuka is the Japanese cold ramen-noodle dish especially popular during summer.
It consists of chilled Chinese-style noodles topped with colorful ingredients such as cucumber, tomato, ham, chicken, chashu, strips of omelet, menma, or pickled ginger. Rather than a steaming ramen broth, it is usually dressed with a chilled tare, commonly based on soy sauce and rice vinegar or on sesame flavors. This is why descriptions sometimes loosely call it a cold-broth ramen dish.
The dish is generally traced to the Chinese restaurant Ryutei in Sendai, which introduced an early version in 1937. It was inspired in part by liangbanmian, a Shanghainese cold-noodle dish. The name hiyashi chuka became established in Japan in the late 1950s.
Hiyashi chuka is easy to confuse with tsukemen, because both may involve cooled noodles. Tsukemen keeps the noodles and dipping soup separate, while hiyashi chuka presents chilled noodles with toppings and sauce together. In some regions it is also known by names such as reimen.