At almost every Chinese restaurant in Japan you’ll find a dish called tenshindon. “Tenshin” is the Japanese way of saying Tianjin, a port city in northeast China, and “don” is a dish that consists of a bowl of rice with various toppings.

Tenshindon is usually a crabmeat omelette on rice, with a thick, glossy topping of either soy or sweet and sour sauce. Some­times the omelette contains other ingredi­ents, such as pork or prawns.

Tianjin was made a treaty port in 1860 during the second opium war, and many countries, including Japan, estab­lished concessions in the city and began trading. A significant Japanese population in Tianjin meant the city was familiar to many of those back home.

Fumiyoshi Yokota, a professor of Chinese cuisine, dedicates an entire book to the food of Tianjin. In the 2009 work, the title of which translates to The Research of Chinese Food Culture: Tianjin, Yokota says there are two legends about how tenshindon came to be: one saying it originated in Tokyo, the other, Osaka.

The Tokyo story is that the third-gener­ation operator of Rai Rai Ken, the restaurant that popularised shoyu (soy sauce) ramen, had just returned from serving in the army during the second Sino-Japanese war (1937-45). One day, a hungry customer walked in and asked to be served as quickly as possible. A cook com­bined egg and crab to make an omelette, served it on top of rice and added the sauce he used for sweet and sour pork. Rai Rai Ken’s owner called it tenshindon, as there were many Japanese soldiers in Tianjin, and the city was well known among Tokyo’s residents.

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The second story has it that in the years fol­low­ing the second world war, when resources were limited, the owner of a Chinese restaur­ant, Taishoken, in Osaka, created a dish that made the most of the abundance of Japanese blue crabs in Osaka Bay, as well as shrimp in the city’s rivers. He was originally from Shandong province, just south of Tianjin, and said that when Tianjin people had to eat frugally, they would fish for crabs and shrimp in their bay and rivers, and because they wouldn’t have been able to cook more than one dish, each person would be rationed a small amount, which was placed directly on top of their rice. In the style of north­eastern Chinese cooking, he added a sauce that was heavy on soy and salt to create tenshindon.

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Still another story is that the dish got its name from a time when Japan imported rice from Xiaozhan, a town in Tianjin, although that doesn’t explain the toppings, which are the most distinctive attribute.

Whatever its origin, tenshindon’s popu­lar­ity has not waned, and its curious name has not only been immortalised on menus, but also in one of Japan’s most successful manga series, Dragon Ball. The creator, Akira Toriyama, is known for his love of food-related puns, and he named one of his characters Tenshinhan – “han” means rice.