Zenzai is a Japanese bean dish made of small red adzuki beans, boiled, and sweetened with white or brown sugar. It is sometimes described in English as red-bean porridge. The ingredients are simple, but it takes time to make.
It can be served warm or cold, Shiruko, aka oshiruko style, or Zenzai style.
The beans can either be mashed into a paste, or just crushed, with some slightly crushed beans mixed into the paste, to give a varied texture. If served as a paste, it is more likely to be called zenzai. This version is more common in western Japan. Shiruko-style is generally more watery, like a soup, and is often served warm, particularly during the winter.
The mashed beans are usually strained to get the skins off, but sometimes the beans are left pretty much whole, with the skins on. They are sometimes puréed by pressing them through a strainer.
Shiruko style is served with a piece of mochi in it, which acts as a dumpling. The mochi may be grilled, if being served shiruko style with warmed beans. If it is served with buckwheat dumplings in the soup instead of mochi, it is called Soba Shiruko. It is often served with something sour or salty on the side, such as pickles, to give a taste contrast. That something might be shiokombu or umeboshi. Shiruko is served at New Year in Kagawa Prefecture instead of zoni.
Okinawa Style Zenzai is made with brown sugar, topped with a mochi rice cake, then topped with shaved ice. Some beans are left whole in the bean mixture.
Soba zenzai, aka soba-gaki zenzai, is Zenzai served with buckwheat dumplings or a thick mound of buckwheat porridge served on the side of the paste instead of mochi.
Zenzai is also sold at restaurants called “kanmi-dokoro” as a Wagashi snack between meals. When topped with a fruit sauce such as lemon, strawberry or melon, it is called “Kanadoki.” It can also be topped with crushed ice.
You can now get Zenzai canned, and ready to heat, or in a powder that you add hot water to.
Zenzai is not a centuries’ old dish. It has only been made since about the 1700s when sugar started becoming available in Japan.
It was documented in 1852 in the Morisada Manko: “In Edo [Ed: Tokyo] the skins of adzuki beans are removed, and the beans are boiled with white or unrefined sugar and a cut slice of mochi rice cake. The soup is called shiruko. In the Kyoto and Osaka areas, soup with the bean skins removed is called shiruko or koshian-no-zenzai.”
In Okinawa, Zenzai was originally made with green beans. They switched to using red beans after the Second World War.
Zenzai used to be sold door to door by pedlars.