Onigiri

Onigiri (おにぎり, お握り or 御握り), also known as omusubi (おむすび or お結び) or nigirimeshi (握り飯), is a Japanese rice ball made from white rice. It is usually formed into triangular or cylindrical shapes, and wrapped in nori (seaweed). While modern onigiri can be filled with a wide variety of ingredients, including both savory and sweet fillings, traditional fillings are often salty or sour, such as salted salmon, umeboshi (pickled Japanese plum), katsuobushi (smoked and fermented bonito), kombu tsukudani (sweet simmered kelp), tarako or mentaiko (pollock roe), or takanazuke (pickled Japanese mustard greens). Because it is easily portable and eaten by hand, onigiri has been used as portable food or bento from ancient times to the present day. Originally, it was used as a way to use and store left-over rice, but it later became a regular meal.

Description: Wikipedia — Onigiri, CC BY-SA 4.0