The shiny, sweet black soybeans called Kuromame are served on New Year’s Day as a part of Osechi Ryori (traditional New Year’s Meal) in Japan.
Kuromame (Sweet Black Soybeans) literally means “black bean (黒豆)” in Japanese, and it is often served on New Years Day as a part of Osechi Ryori (traditional New Years Meal). The shiny black beans are beautifully contrasting with red lacquer “jubako” (お重箱) container, which holds all different kinds of colorful traditional meals.
Eating kuromame is considered good for your health for the new year. My parents encouraged me to eat some kuromame on New Year’s Day but this is actually one of my favorite items among all the New Year’s dishes. Kuromame’s sweet and slightly savory flavor can be quite addicting.
By the way, kuromame is black soybeans and not black beans. Kuromame recipe is pretty simple but the soybeans have to be soaked for overnight and simmered on very low heat for a long time, some recipes say to cook on low heat for 8 hours!
I only cook for 4 hours till my black soybeans are tender. I use a heavy-bottomed cast iron pot, which retains heat very well. Please test the doneness of your black soybeans and adjust your cooking time.
If you have an Instant Pot or a pressure cooker, you can speed up the cooking process (15-minute high-pressure cooking!). Check out my Instant Pot Kuromame recipe.
The Trick to Achieve Beautiful Black Color on Beans
Most of the traditional kuromame recipes require 2-3 “rusty” iron nails but it’s hard to find them! So in my recipe, I used Lucky Iron Fish that I purchased on Amazon.
The reason why the Japanese put nails to cook kuromame is that rust (iron oxide) from nails has a chemical reaction with tannin in the beans, which helps the beans turn dark to a rich black color.
I hope this delicious kuromame will bring you health for the new year.
Pressure Cooker Kuromame
If you have an Instant Pot or a pressure cooker, check out my Instant Pot Kuromame recipe.
Japanese Ingredient Substitution: If you want to look for substitutes for Japanese condiments and ingredients, click here.
Kuromame (Sweet Black Soybeans)
- Gather all the ingredients. You will also need an Otoshibuta (drop lid), a large pot with a lid, and 2-3 rusty iron nails (traditional method) in a cheesecloth or Iron Fish.
- Rinse black soybeans under running water and discard bad ones. Some beans have skin that is half-peeled off, but you don’t have to throw them away.
- Put black soybeans, water (1200 ml, 5 cups), and the rusty nails or Iron Fish in a large pot. Let it soak overnight (6-8 hours).
- After being soaked, add sugar and salt and gently mix. Keep the nails/Iron Fish in the pot.
- Start cooking over medium heat. Once boiling, you start to see white bubbles.
- Thoroughly skim the scum and foam off the surface.
- When it's done, put an Otoshibuta and a regular pot lid. The otoshibuta is to keep the soybeans under the cooking liquid (which is to prevent the beans from getting wrinkles). Reduce heat to low and simmer (make sure beans are not bouncing around) for 4 hours or until the beans are tender.
- Check inside the pot a few times to make sure there is enough cooking liquid. If not enough, add water (I added 1 cup water). Skim the surface if needed.
- Check if the beans are tender by mashing a bean with two fingers. Take out the rusty nails/Iron Fish.
- When the beans are tender, add soy sauce and mix well.
- Remove from the heat and place the parchment paper on top of the surface to prevent the beans from getting wrinkles. Once cooled, keep in the refrigerator overnight so the soybeans will turn darker and absorb more flavor.
To Serve and Store
- The following day, you can transfer the soybeans to an airtight container and store in the refrigerator for up to 4 days or in the freezer for up to a month.
- Serve the soybeans chilled or at room temperature in a bowl.
Leftover Cooking Liquid
- You can use the leftover cooking liquid to make jello (using gelatin, agar, or kanten), latte, sweets, bread, oshiruko (zenzai), and more!
Editor’s Note: This post was originally published on December 27, 2012. New images have been added to the post in December 2019.