The Japanese street-food snack of grilled octopus-filled batter balls is called takoyaki.
Takoyaki are made by cooking a wheat-flour batter in a specially molded pan with round cavities. A piece of octopus, usually called tako, is placed inside each portion along with ingredients such as green onion and pickled ginger. Vendors turn the balls repeatedly so they cook into spheres with browned exteriors.
The snack was popularized in Osaka in 1935 by street-food vendor Tomekichi Endo. Its name combines tako, meaning octopus, with yaki, meaning grilled or cooked.
Takoyaki is commonly topped with takoyaki sauce, mayonnaise, aonori seaweed, and bonito flakes. The center can remain extremely hot after cooking, so it is often eaten carefully. Although regional and modern fillings exist, octopus is the defining traditional filling.