sweet black soybeans
Although at first glance they could from afar appear to just be black beans, kuromame are sweetened black soybeans. They’re associated with New Year’s alongside many other snacks.
The process to make kuromame is pretty simple, but it takes quite a while. From start to finish it could take up to 24 hours (or in certain recipes, longer!), but luckily much of this time just consists of waiting, so it doesn’t require much actual work to cook.
Recipes vary, but in general kuromame are made by soaking black soybeans overnight (or the equivalent) and then simmering them on low heat for many hours with sugar until the beans are tender and can easily be crushed. Sometimes, a bit of salt and/or soy sauce is included.
The simmering process historically included dropping a few rusty nails — yes, you read that correctly — into the pot to be cooked with the beans, since the chemical reaction would help make the beans dark and shiny. Now, there are better ways to achieve this by either using a cast iron pot or purchasing a special iron figurine to drop in with the beans.