Vegetarians in Japan will quickly learn that there are two common options for the filling inside the nori-wrapped onigiri (rice balls) found in convenience stores: umeboshi (pickled plum) or kombu (seaweed — though I recently read that even certain types of prepared kombu might contain some fish extract).

However, there is one less common onigiri option that I quickly snap up whenever it's offered: takana. Takana, or more accurately, takana-zuke, is made from pickled mustard leaf, and is mildly spicy and crunchy. For a while I was happy enough just knowing that it was a vegetarian onigiri option, but recently I had the urge to investigate where else I could find this delightful food.

Pickled mustard greens find their way into many Asian cuisines, but I was surprised to find the various creative uses for takana-zuke in Japan. You can eat it hot or cold, alone or as okazu (a small side dish accompanying rice), as a topping for ramen or okayu (rice porridge), or as part of a veggie stir-fry.