Onigiri is the Japanese answer to the sandwich. These balls of rice have aristocratic beginnings, much like the sandwich, and similarly have evolved into a casual and convenient food that anyone can make at home. The Tale of Genji, written by Murasaki-Shikibu in Japan during the 11th century, makes the first mention of the eating of rice formed into balls. Now, nearly a thousand years later, onigiri is a staple of the Japanese diet, though it is only starting to gain…