Tamagoyaki is a Japanese omelet dish made by using a unique cooking method - the eggs are folded into themselves until they are fully cooked. Although the omelette has no fillings, it is usually seasoned with sugar, mirin, and soy sauce. Tamagoyaki can often be found in bento boxes, and it is traditionally served either for breakfast or as a sushi topping.
The name of the dish can be literally translated to eggs cooked over dry heat. The simple tamagoyaki first became popular in the 1950s, when the government started to encourage parents to give more protein to their children, and the farmers started to keep more chickens.