Takoyaki is a ball-shaped Japanese snack made of a wheat flour-based batter and cooked in a special moulded pan. It is typically filled with minced or diced octopus (tako), tempura scraps (tenkasu), pickled ginger, and green onion. Takoyaki are brushed with takoyaki sauce (similar to Worcestershire sauce) and mayonnaise, and then sprinkled with green laver (aonori) and shavings of dried bonito. There are many variations to the takoyaki recipe, for example, ponzu (soy sauce with dashi and citrus vinegar), goma-dare (sesame-and-vinegar sauce) or vinegared dashi.
Takoyaki was first popularized in Osaka, where a street vendor named Tomekichi Endo is credited with its invention in 1935. Takoyaki was inspired by akashiyaki, a small round dumpling from the city of Akashi in Hyōgo Prefecture made of an egg-rich batter and octopus. Takoyaki was initially popular in the Kansai region, and later spread to the Kantō region and other areas of Japan. Takoyaki is associated with yatai street food stalls, and there are many well-established takoyaki specialty restaurants, particularly in the Kansai region. Takoyaki is now sold at commercial outlets, such as supermarkets and 24-hour convenience stores.
(source: Wikipedia – https://en.wikipedia.org/wiki/Takoyaki)