Gemlike Sweet Black Soybeans called Kuromame are a classic dish for Osechi Ryori or traditional Japanese New Year foods. The shiny beans symbolize good health in the new year. Try my pressure cooker recipe to shorten cooking time without sacrificing flavor.
Please note that this recipe requires a minimum soaking time of 4 hours for the dried beans; I also recommend a resting time of 8 hours once cooked, but this is not required. Please read and follow the package instructions for your black soybeans. My package directions say to soak for 4–5 hours, so I soaked them for 4 hours. For testing purposes, I tried soaking the same brand of soybeans overnight, and they came out a bit too soft. You may need to test to see how long you want to soak your soybeans.
I recommend making this recipe 1–3 days before you plan to serve. For more helpful tips on planning your Japanese New Year feast, please read my A 5-Day Osechi Cooking Timeline blog post.
Gather all the ingredients.
To Soak the Soybeans
Gently rinse 8.8 oz kuromame (black soybeans) under cold running water. The skins are very fragile, so handle with care. Some beans have skin that is partially peeled off, but you can use those in this recipe. Discard any damaged soybeans. Drain well.
Put the soybeans in the inner pot of an Instant Pot. Add 4 cups water to the pot. Depending on your package instructions, soak the soybeans for 4 hours or overnight on the counter in the wintertime (or in the refrigerator in the summertime and in warm climates).
To enhance the color of the soybeans, we use rusty iron nails or Lucky Iron Fish to cook with the soybeans. (Read more in the blog post.) If you use rusty iron nails, clean 2–3 nails and wrap them in cheesecloth. Add the nails or the Iron Fish to the water with the soybeans.
To Cook
After soaking, put the inner pot back into the Instant Pot (keep the nails or Iron Fish in the pot). Add 1 cup sugar, 2½ tsp soy sauce, and ½ tsp Diamond Crystal kosher salt. Mix gently.
Close the lid and set to High pressure for 15 minutes (it will take 10 minutes to pressurize). Make sure the steam release handle points to Sealing and not Venting. The float valve will rise when pressurized.
When it’s finished cooking, the Instant Pot will switch automatically to the Keep Warm mode. Let the pressure release naturally for about 45 minutes. Open the lid and check if the beans are done cooking; they should be tender enough to mash between two fingers. Then, take out the inner pot from the Instant Pot and remove the nails or Iron Fish.
Pour the cooked soybeans and cooking liquid into a large airtight container. Leave uncovered and let the soybeans cool completely.
To Rest (recommended)
Once cooled, the Kuromame are ready to eat. To yield a more striking black color and absorb more flavor, cover the container and let the soybeans soak in their cooking liquid for 8 hours or overnight in the refrigerator.
To Serve
The following day, serve the Kuromame in a bowl without the cooking liquid. You can serve it either chilled or at room temperature. If you'd like to make it more festive, you can garnish it on top with edible gold leaf flakes (optional).
To Store
Store the Kuromame in an airtight container, with enough cooking liquid to cover them, in the refrigerator for up to 4 days or in the freezer for one month.
To Use the Leftover Cooking Liquid and Kuromame
You can use the leftover cooking liquid to make Oshiruko (Zenzai), black soybean latte, and jello (using gelatin, agar, or Kanten). You can use the leftover Kuromame to make pound cake and Steamed Cake.