Kuromame (Japanese Black Soybeans)

This easy recipe and video will show you how to make plump, tender Kuromame for Oshougatsu that look like they're ready to burst from their glossy black skins. With a bit of science, it's easy to make this Osechi Ryōri staple using just a few basic ingredients.

Recipe Video Pin

Kuromame are black soybeans cooked in a sweet and savory syrup until the midnight black skins melt away in your mouth to reveal the velvety beans in the center. It's a staple of Osechi Ryori or Japanese New Years' cuisine.

Kuromame (黒豆)

New Year's or Oshougatsu is a time for rest and reflection here in Japan, and it's a time where families gather to visit shrines and feast on traditional dishes like this Kuromame. Kuromame literally translates to "black bean," and it's a staple of Osechi Ryōri (おせち料理) or the traditional New Year's meal eaten on New Year's Day.

Although it's a simple dish with just a few ingredients, it can be very challenging to get the beans to turn out with piano black skin that looks like they're about to burst. This makes Kuromame one of the more difficult New Year's dishes to prepare.

In this recipe, I've combined a few techniques to ensure you get plump beans with midnight black skin that melts away to reveal a rich and creamy center.

Why This Recipe Works?

Soaking the black soybeans in water overnight with baking soda and salt helps break down pectin in the skins. This makes it easier to achieve a velvety bean with skin that practically melts in your mouth.
Adding a source of iron to the pot with the kuromame intensifies the black color of the beans while preventing the color from fading. As the iron dissolves, the ions form complexes with the anthocyanin in the beans, which results in a bathochromic shift and stabilizes the pigments. Traditionally, rusty iron nails were used, but these days you can buy food-safe pieces of iron that come in different shapes. If you want to pick up the iron cucumber I used, you can get it here on my online kitchen tools shop.
Using a pressure cooker reduces the cooking time from 3-4 hours to around 30 minutes.

With impossibly shiny black skins that melt away to reveal a creamy bean inside, kuromame is a classic staple of Osechi Ryori (Japanese New Years' cuisine.)

Ingredients for Kuromame

Black soybeans (Kuromame) - Also known as Japanese Black Beans, Kuromame are a type of soybean with black skin and a white interior. These are not to be confused with black turtle beans used in Latin American food, which have a different texture and taste and are not interchangeable. As for the type of black soybeans to use, the best ones come from Tanba in Hyogo prefecture. They can be very expensive, but they're worth the extra money if you can find and afford them.
Salt - Salt has two jobs here. Once dissolved in water, the sodium ions swap places with the calcium in pectin, which weakens the structure of the beans. Contrary to "common wisdom," adding salt to beans not only speeds up the cooking process it also helps prevent the beans from splitting by making the skins more flexible. The second purpose of the salt is to season the beans.
Baking soda - Baking soda not only adds sodium ions to the soaking liquid but also raises the pH of the water, which helps break down the pectin in the beans. This helps them soften much faster and allows the skins to virtually melt away in your mouth.
Sugar - Sugar was an expensive ingredient historically, so foods cooked with sugar show the care and effort put into making it. This is why traditional celebratory foods often contain a lot of sugar. Within the context of Osechi Ryōri, many of the dishes are either salty or sour, so it's a nice counterpoint to have a sweet contrast. I don't like my kuromame to be overwhelmingly sweet, so I use a lot less sugar than most recipes call for, but you can add more if you want your beans to be sweeter. I also like the added flavor of using minimally processed sugar like evaporated cane sugar.
Soy sauce - Soy sauce is added to balance out the sweetness of the other ingredients while imparting umami to the beans.

How to Make Kuromame in a Pressure Cooker

Rinse the black soybeans in cold water until the water runs clear. Drain them well and add them to a bowl with five cups of water, the baking soda, and the salt. Stir the mixture to dissolve the salt and cover the bowl to let the beans soak overnight.

To cook the kuromame, dump the beans and soaking liquid into a pressure cooker and add one cup sugar and a tablespoon and a half of soy sauce. Next, add a food-safe piece of iron and seal the cooker's lid.

Set the pressure cooker to high pressure and quickly bring it up to pressure over high heat. Once you hear steam escaping, turn down the heat, so you still get a steady stream of steam, but it doesn't sound like a jet taking off. Set a timer for twenty-five minutes.

When the timer goes off, turn off the heat and let the pressure cooker cool to room temperature without opening it.

You can eat the black beans at this point, but I prefer letting the kuromame rest overnight in the fridge with the iron and braising liquid. This allows the flavors to mature while making the beans an even deeper black.

Kuromame skin will get wrinkles if exposed to air so keep the beans submerged until you're ready to serve them and strain only the portion you want to eat.

These sweet black soybeans or kuromame are piano black and melt-in-your-mouth tender.

How to Make Kuromame In a Pot

The process for preparing the beans is exactly the same, but instead of putting them in a pressure cooker, you just need to add the beans, seasonings, and iron to a saucepan or better yet a large cast iron pot.

Bring this to a boil and skim off any scum that floats to the surface. Turn down the heat to maintain a gentle simmer, cover the beans with an otoshibuta (drop lid), and cook until the beans are very tender for 3-4 hours.

FAQ

What is Kuromame?

Kuromame (黒豆) literally means "black bean" in Japanese. It refers to both black soybeans(Glycine Max) and a dish made by cooking them in a sweet syrup. It's a standard part of Osechi Ryori (おせち料理) and symbolizes diligence and hard work due to the word for diligence (まめ - mame) being pronounced the same as the word for bean (豆 - mame).

How do you pronounce Kuromame?

Kuromame is a four-syllable word that's pronounced as follows:

ku like cool
ro like the “ro” sound does not exist in the English language, and the best way to make it is to say the word "roll" with the tip of your tongue at the front of your mouth.
ma like mall
me like men

Is Kuromame vegan?

As long as the sugar you are using is plant-based, this kuromame recipe is vegan-friendly.

Do I have to add iron?

Adding the iron is cosmetic, so if you're okay with the beans not being midnight black, then you can skip it.

Can I use iron supplements?

As long as the supplements don't contain anything else (such as collagen or vitamin C), you can add a few supplement tablets to the pot instead of the piece of iron.

How do I serve Kuromame?

Although it's most commonly served as part of a traditional Japanese New Year’s meal, the sweet taste of the shiny black beans makes it the perfect accompaniment for saltier dishes. This makes it a popular addition to bento box lunches.

📖 Recipe

Kuromame

5 from 3 votes

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Prep Time 5

Cook Time 30

Total Time 1 35

Yield 8 servings

Equipment

Pressure cooker

Iron Cucumber

Units

Ingredients

250 grams black soybeans
5 cups water
¼ teaspoon baking soda
¼ teaspoon salt
1 cup evaporated cane sugar 200 grams
1 ½ tablespoons soy sauce

Instructions

Wash the black soybeans until the water runs mostly clear.
Drain the beans and add them to a bowl with the water, baking soda, and salt. Give them a stir and then cover and let the beans soak for at least 12 hours.
When you're ready to cook the beans, dump them into a pressure cooker along with the soaking liquid and add in the sugar and soy sauce. Add in your piece of iron and close the lid of your pressure cooker.
Set the cooker to high pressure and put it over high heat to quickly bring it up to pressure. Once you hear it start to whistle, turn down the heat to maintain a gentle stream of steam escaping and then set a timer for 25 minutes.
Turn off the heat when the timer is up and let the pot cool down to room temperature. Then, transfer the beans and the piece of iron to a container and refrigerate the Kuromame overnight to get a nice dark color and allow the flavors to mature.
To serve the next day, drain only the portion of beans you plan to serve, and garnish with gold leaf (optional).