Onigiri are portable parcels that fit in the palm of your hand (nigiri means "to squeeze"). They are sold in tiny rice shops, izakayas, department-store food halls, and convenience stores, like 7-Eleven. They look a little bit like sushi, but they aren't seasoned with mirin the way sushi rice is. Some are wrapped in crisp nori or fresh shiso leaves; others are naked or made with rice mixed with ingredients like sesame seeds. I like the classic fillings, such as salmon, kombu, and tarako (salted cod roe). Umeboshi (pickled plum) is also quite popular, as is tuna, shrimp tempura, and even cheese.