The famous triangular- or wheel-shaped rice balls called Onigiri are something that can be found everywhere and anytime in Tokyo. People eat them for breakfast, kids take them to school in their Obento boxes, they are the salariman's favourite for lunch break and a good midnight snack available at the conbini around the corner. Although they look pretty small, they are quite filling due to the big amount of rice that is pressed into the ball shape.
And the good thing about it: many Onigiri are vegetarian! Basically they are made out of freshly cooked Japanese-style rice, a little salt and Nori seaweed plus a wide variety of fillings. The most traditional one would be a pickled plum called Umeboshi (look out for 梅干 or 梅ぼし und you will get this vegan snack) which is extraordinary popular not only with patriots who see the Japanese flag in the red round plum surrounded by white rice. Umeboshi are also said to be very healthy despite their extreme saltiness. Most people are irritated by the salty sour little fruit when they eat it for the first time, but it is indeed a delicassy worth a second try. I love it!
Other vegetarian options are for example Onigiri sprinkled with black sesame or Shiso (紫蘇 or しそ), in English often referred to as Perilla - a dark red herb with a very fresh and distinct flavour.
Another variation is an Onigiri that consists of rice that is mixed with black beans - these are usually not wrapped in seaweed. But with these you have to look out, sometimes they are flavoured with Dashi, that might not be vegetarian! A closer look on the list of ingrediences (if you buy it in a conbini and are able to read Japanese) has to be made if you want to be sure.
You can also buy Onigiri in one of the countless shops, commonly found at train stations. Here they are made freshly and most of the times are offered beside an array of other Obento specialities. These often taste better, but there is no list of ingrediences and you will have to ask whether it is vegetarian or not (unless you take the Umeboshi version that is vegan for sure). But even a positive answer is not at all an assurance of an animalfree rice ball.. The one you see on my photo above looked great: wrapped in spinach (?or something similar?) instead of seaweed, a variant I never saw before that woke my interest. So I asked at the counter in Japanese "is it vegetarian? without meat, without fish?", the vendor said "yes bejitarian", I took it, bit into it - the filling was Katsuobushi, fish flakes! When will it finally become known that fish is still fish even though it does not look like it anymore... and that it won't become more vegetarian by processing it to flakes!
Well, next time I will go on the safe side, have Umeboshi again or buy it at one of the organic food stores that spring up like mushrooms in some areas of the city. Here at least the shop assistants understand the meaning of the word "bejitarian".
Making Onigiri yourself is of course the safest way. You can find a recipe here.