Kuromame (Sweet Black Soybeans) 黒豆

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Kuromame (Sweet Black Soybeans) | JustOneCookbook.com

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 shinny black beans are beautiful 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 item among all the New Years dishes.  Kuromame’s sweet and slightly savory flavor can be quite addicting.

Kuromame (Sweet Black Soybeans) | JustOneCookbook.com

By the way, if you use “black bean” for cooking, please note kuromame is black soybeans.  Kuromame recipe is pretty simple but the soybeans has to be simmered on very low heat for a long time.  When it comes to traditional food and recipes, each family has a slightly different method to make them which passes down to generations.  For kuromame, I’ve seen recipes which requires 8 hours but others are shorter.

Kuromame (Sweet Black Soybeans) | JustOneCookbook.com

Most of traditional kuromame recipes require 2-3 “rusty” iron nails but for today’s recipe I made without them as an experiment.  The reason why the Japanese put nails to cook kuromame is that rust (iron oxide) from nails has chemical reaction with tannin in the beans, which help the beans turn dark to a rich black color.

How was the result?  Maybe the “blackness” might have improved if I had put nails, but I’ve seen beautiful black kuromame which had been cooked without nails before.  So at the end, it’s really up to you.  The taste was excellent!

Hope these delicious kuromame will bring you health for the new year.

Kuromame (Sweet Black Soybeans) | JustOneCookbook.com

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Kuromame (Sweet Black Soybeans)
Prep time
Cook time
Total time
Serves: 6-8
You will also need
  • A large pot with a lid
  • Otoshibuta
  • 2-3 rusty iron nails*
  1. Rinse black soybeans and discard bad ones. Some beans have skin that is half peeled off, but you don’t have to throw away.
  2. Put black soybeans and the right amount of water in a large pot and let it soak overnight. I soaked for about 12 hours.
  3. After being soaked, add sugar and salt and gently mix.
  4. Start cooking over medium heat and put an Otoshibuta and a regular pot lid. The otoshibuta is to keep the soybeans under the liquid (As soon as the beans are exposed to air, they'll start wrinkling.) and the regular lid is to keep the heat in the pot.
  5. Once boiling, you start to see white bubbles.
  6. Take out the two lids and thoroughly skim the white scum off the surface. When it's done, put back two lids.
  7. Reduce heat to low and simmer (make sure beans are not “bouncing around”) for 4 hours or until the beans are soft. Check if the beans are cooked by mashing a bean with two fingers. Skim the white scum off the surface a few more times while simmering.
  8. If it’s easily mashed, add soy sauce.
  9. Remove from the heat and place the parchment paper on top. As soon as the beans are exposed to air, they'll start wrinkling. To avoid that, you need to cover the surface of the liquid with parchment paper or plastic wrap.
  10. Once the pot is cooled down, keep in the refrigerator overnight. This will help the soybeans turn darker and absorb more flavor.
Traditional recipes require 2-3 “rusty” iron nails. If you use nails, choose very rusty nails, wrap them in cheese cloth and put in the water when you soak over night. Don’t take the nails out until you complete cooking.

The ratio for black soybeans : sugar : water = 1 : 1 : 6.

Must be consumed in 3-4 days, otherwise freeze in an airtight container.

Recipe by Namiko Chen of Just One Cookbook. All images and content on this site are copyright protected. Please do not use my images without my permission. If you’d like to share this recipe on your site, please re-write the recipe in your own words and link to this post as the original source. Thank you.



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  1. I can’t wait to make these Nami. I don’t know that I will put in the rusty nails though, LOL. I love the color of the beans.. I will let you know how they turn out. Thanks for sharing this recipe. Wishing you a Healthy & Happy New Year to you and your family and

  2. Another amazingly beautiful dish, Nami. As another poster said, though, I wouldn’t add the rusty iron nails. :) I can’t believe how perfect your beans are and the setting… bowl, lighting, greenery, serving pieces, they all set off the recipe.

  3. These beans look so good! I really like the tidbit about the rusty iron nails. I don’t think I will use them, but would you get similar results by using a cast iron pot?

    It’s a lovely way to start out the new year – with something healthy. It’s Korean tradition to eat tteok manduguk (dumpling & rice cake soup). I will have to have a side of these beans with it! Happy New Year to you and your family! :-)

    • My cast iron pot has enamel coating on it, so it doesn’t work but Marc of No Recipe suggested the cast iron method for this recipe, so I’m sure it will work. I love the Korean traditional New Year food! Happy New Year to you and your family! :)

  4. What a great post! I’ve seen these black soy beans before at the Asian grocery but never knew what to do with them. Glad you gave us the recipe. That’s so interesting to use black rusty nails. I believe you. We have a Filipino recipe for a soup dish that suggests the use of a fork inside the stew while cooking. Thanks again for sharing, Nami. Have a great Happy New Year! Catch you in 2013!

  5. Beans are always good in nutrition and as far as I know black beans has more nutrition. Previously the only dish I know how to make use of black beans is brewing as soup and now looking at your post, I can make it to go with porridge!

  6. Eha

    The beans look moreish and the use of and amount of sugar is interesting. Hmm – don’t think I would add the rusty nail: there obviously for the iron, of which we so oft can have too much :) Hope you are having a relaxing and happy wait for the New Year bells to ring!! Much love from across the Pond!

  7. I’m always just so taken by your photos Nami. They are so incredible. The colors are so vivid and the pictures are so alive. I feel like I could just reach through and snack on some of these beauties. They sound very good. I know Miss A especially would enjoy these. Happy New Year to you and your family! I hope you have a fantastic year. :)

  8. It’s always lovely to learn something new every day. That’s why I love it so much whenever I visit your blog. I always learn something new in traditional Japanese cooking, plus, I can drool over your wonderful pictures. :) Didn’t know the traditional way is to put nails to cook these black soybeans. I don’t think I should do that cos I probably will forget to take all of them out. hahaha…. Thanks for sharing such a beautiful recipe. Wish you and your family a prosperous 2013!

  9. Haha…My grandma was putting rusty nails before she cooked beans:) I haven’t done that in so many years, probably since I came to US..total flashback! Delicious looking beans… perfectly made!!!! Have a relaxing weekend! xo

  10. Sylvia

    The colour and sheen of the soy beans are lovely! I’ll be quite afraid to add rusty nails to it though even with your explanation! 😉 I wanted to make your sesame cookies over Christmas but I realised that I didn’t have ground almonds! Typical of me… not checking if i had all the ingredients before wanting to make them! haha

  11. slow-cooked beans are my all-time favourite, and the simpler the better. This is brilliant, and I will definitely try this.. I’ll keep my eyes open for black soy beans, which I have never come across before. adore the rusty nails! what a fascinating recipe, thanks, Nami.

  12. Kimmi

    The beans look so beautiful and shiny! =) I usually don’t eat beans as they are – except maybe oshiruko – but I’m curious to try this recipe. I’m not sure if my beans will turn out as beautiful though~

  13. Wow… these look like little gems…they are so shiny. I eat a variety of foods on New Years day for luck, health etc…. Now I will have to add these onto the list. :) Wishing a wonderful New Year to you and your family!!

  14. These have such gorgeous color. And your photos really showcase the beans nicely. Great highlights on the beans in all the pictures, the second one in particular (but really, all of them). Love the colors in the first picture. Anyway, I’ve never had these, but they so easy to make, and look so nice, I’ll have to try them. Thanks so much.

  15. I think I tried something like this as a banchan at a Korean restaurant. It was delicious! I think I’ll try cooking this in a cast iron Dutch oven. Maybe the iron from the oven will leech into the beans.

  16. I’m so sorry I have almost missed this another less known, but certainly delicious Japanese dish. I love the rusty nail idea! I wonder if they are dangerous once boiled… You beans look lovely! I hope you are having wonderful holidays.

  17. Hi,

    I’m not one to write messages so this is a first:) I just wanted to let you know, that I visit tons of cooking sites, and or blogs, and yours is my favorite:) I love your pics, the way you explain the recipes, it’s all great!!! I hope you have a fantastic New Year also, again, thank-you very much for your site!!!:):):)

    • Hi Tracy! Thank you so much for taking your time to write the kind message. It really made my day! Happy New Year to you and your loved ones! :)

  18. Mark & I are talking about making our own soy bean once we get our own place. I have to check if we can find black soybeans in Minneapolis. They are a lot more flavorful than the white ones. Tough nails I have:) Itadakimasu!

  19. Serena

    Happy new year Nami! Wishing you and the people you love all the best. And for us, your spoiled followers, other delicious recipes like these :)

    P.S. Last night I had for dinner your Shiojake. Superb. Not to mention the Clam Miso Soup, the Yudofu and Yaki Onigiri, Boiled Squid, Spinach Ohitashi… Your clues are always so clear that is impossible to go wrong.

    • Happy New Year Serena! Wow, you made so many of my recipes!! Thank you for trying them and I’m really happy to hear you enjoyed them and my instruction was clear. You made my day! :) Thank you for your feedback!

  20. なみさん、新年明けましておめでとうございます!久しぶりになみさんのブロッグに遊びに来ました。相変わらず素敵な写真を見せてくれましたね。
    I really love the glossy appetizing look of the kuromame! Wonderful!

  21. I’ve been lucky enough to attend several Japanese New Year parties (attending one tomorrow, too) and this is one of my favorite dishes. Last year a good friend shared brought the kuromame and I couldn’t get enough. Looking forward to having a taste again tomorrow night. Now I’ll know where to go when I feel like making my own–thanks for sharing your recipe, Nami. Happy New Year!

  22. I’ve been looking for this everywhere! They are my FAVORITE! My grandma always make me eat 黒豆 all the time, and I can’t wait to find these ingredients in Asia! Thank you!!!!!