Nothing sounds better than a warm bowl of homemade Zenzai (Oshiruko) or sweet red bean soup with toasted mochi rice cakes! I’ll show you 3 ways to make this popular winter dessert in Japan with either homemade or store-bought ingredients.

Zenzai (ぜんざい) is a traditional Japanese dessert soup made with azuki beans. This sweet red bean soup is served hot with mochi (rice cake) or shiratama dango (glutinous rice flour dumplings) inside the soup.
Slightly sweet, with a gentle fragrance from the red beans, the dessert soup has the instant magic of warming up one’s soul. The toasty, chewy mochi makes everything even better! It is one of those dishes that brings many cozy memories of my childhood. I couldn’t resist Zenzai whenever it’s offered. Although it’s a wintertime dessert, I crave and enjoy making it all year round (especially in the cooler climate I live in!).
With a pressure cooker or ready-to-use red bean paste, we can make this red bean soup in no time!

What is Zenzai (Oshiruko)?
Zenzai (ぜんざい, 善哉) is basically a soup made from boiling azuki beans with sugar and salt. You might have heard of a different name for this dessert. Oshiruko(お汁粉) or Shiruko is used in the east of Japan where boiled azuki beans are crushed into a smoother paste and become more watery soup than Zenzai.
Quick Review – Zenzai vs. Oshiruko
East of Japan (East of Nagoya, including Tokyo)
- Chunky red bean soup OR soup-less chunky red bean over mochi is called Zenzai.
- Soupy red bean soup without any beans is called Oshiruko.
West of Japan (West of Nagoya, including Osaka)
- Both chunky and fine red bean soups are called Zenzai.

3 Super Easy Ways to Make Zenzai (Oshiruko)
Method 1: Use a Pressure Cooker
If you have a pressure cooker, you can make Zenzai (Oshiruko) much faster. I have an Instant Pot, so here I share how to make the delicious red bean soup using uncooked azuki beans in exactly one hour!
I love my Instant Pots (I have two models this and this) and make this recipe all year round using them. Compared to the stovetop method, pressure cooking really cuts down my time in the kitchen and it’s been a lifesaver! I can do other chores while preparing my favorite, delicious red bean soup!
Method 2: Cook in a Pot over Stovetop
You don’t have a pressure cooker? No worries, I’ll show you how to make it in a traditional method!
Method 3: Use Red Bean Paste
If you want to make Zenzai as quickly as possible, there is even a faster way. Use store-bought red bean paste. You just need to remember they tend to be a bit sweeter than your homemade version, so you might need to adjust the sweetness.
Or if you end up making a big batch of homemade red bean paste (Anko), you can enjoy Zenzai any time! I keep mine frozen all the time and make various Japanese sweets such as Dorayaki, Daifuku, or Dango.

A Great Use of Mochi from Kagami Biraki
Every year January 11th is Kagami Biraki (鏡開き) in Japan. It is a traditional Japanese ceremony to break the ornamental mochi and eat it for good health and fortune for the New Year. You can read more about this cultural ceremony and tradition in my other post.
There is one thing you have to remember for the Kagami Biraki ceremony: never “cut” the mochi when you break it into pieces. The action reminds the Japanese people of Seppuku (切腹), ritual disembowelment during the old times, and they believed it as a sign of bad luck. Therefore, the common way is to break the mochi with a wooden hammer or do it with your hands.
After mochi is broken into pieces, we toast them until nicely brown and put them in Zenzai to enjoy!
Other Delicious Sweets on Just One Cookbook:

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Zenzai (Oshiruko) – Red Bean Soup with Mochi
Ingredients
Using Dried Azuki Beans (makes 4–6 bowls)
- 1 cup azuki beans (7 oz)
- 4 cups water
- 1 pinch Diamond Crystal kosher salt
- ¾–1 cup sugar
Using Store-bought or Homemade Red Bean Paste (Anko) (makes 1 bowl)
- ½ cup sweet red bean paste (anko) (3.5 oz; you can make Homemade Anko)
- ½ cup water (add more if you desire)
- 1 pinch Diamond Crystal kosher salt (to taste)
To Serve
- 4 pieces Japanese rice cake (mochi) (you can buy kirimochi or make my recipe for homemade mochi or shiratama dango)
Instructions
★ Making Zenzai with Dried Azuki Beans (Makes 4–6 bowls) ★
- Gather all the ingredients.
Option 1: Pressure Cooker Method
- Rinse 1 cup azuki beans carefully until the water is clear. Discard any damaged beans that are floating. Drain water and transfer the beans to the pressure cooker (I use an Instant Pot).
- Add in 4 cups water. Cover and lock the lid of your pressure cooker. Make sure the steam release handle points at Sealing and not Venting.
- Turn on your pressure cooker and select High pressure for 15 minutes (or 10 minutes for slightly firmer beans). For an Instant Pot, select Manual or Pressure Cooker mode, select High pressure, and adjust the cooking time.
- If you are using a stovetop pressure cooker, cook on high heat until High pressure is reached. Then, reduce the heat to low to maintain the pressure for 15 minutes.
- When it’s done cooking, the Instant Pot will switch automatically to the Keep Warm mode. Let the pressure release naturally for 30 minutes. Before you open the lid, turn the steam release handle to Venting and release any leftover pressure. If you’re using the stovetop pressure cooker, remove the pot from the heat and let the pressure release naturally.
- Add 1 pinch Diamond Crystal kosher salt (to taste) and ¾–1 cup sugar into the pot.
- Press the Sauté button and select Low heat. Stir occasionally for about 5 minutes until the sugar dissolves completely.
- After cooking for 5 minutes, the soup will be a bit darker in color, too. Keep warm and start preparing the mochi (please scroll down).
Option 2: Stovetop Method
- Rinse 1 cup azuki beans carefully until the water is clear. Discard any damaged beans that are floating, then drain the water.
- Put the azuki beans and 4 cups water in a pot.
- Bring the water to a boil over medium-high heat. Once boiling, put an otoshibuta (drop lid) over the azuki beans. Turn down the heat to medium-low and keep it simmering for the next 1 to 1½ hours. Tip: The otoshibuta will prevent the beans from dancing around too much. You can make your own with aluminum foil.
- Water will evaporate, so add water as needed to keep the beans submerged. After 1 hour, pick up one bean and mash it with your fingers. If it mashes easily, it‘s done. Otherwise, cook for another 15 minutes and check. Add ¾–1 cup sugar and 1 pinch Diamond Crystal kosher salt (to taste) and cook over low heat until the sugar dissolves completely, stirring occasionally. Keep warm and start preparing the mochi (please scroll down).
★ Making Zenzai with Red Bean Paste (Makes 1 bowl) ★
- In a small saucepan, combine store-bought ½ cup sweet red bean paste (anko) or homemade red bean paste and ½ cup water and bring it to a boil. Add 1 pinch Diamond Crystal kosher salt (to taste) and mix well. Adjust the consistency by adding water or reducing the soup. Keep warm and start preparing the mochi (see next step).
★ To Prepare Mochi and Serve ★
- Cut 4 pieces Japanese rice cake (mochi) into halves or quarters and place them in the toaster oven (or the oven). If you‘re using fresh homemade mochi, add it to the soup to warm it up. If it‘s frozen, then boil it in a pot until soft.
- Toast the mochi until puffed up and nicely brown, about 10–12 minutes.
- Serve the red bean soup and mochi in a bowl and enjoy!
Nutrition
Editor’s Note: This post was originally published on Mar 12, 2012. It’s been updated with new images and additional pressure cooking method in the recipe in January 2020.
I had always felt intimidated by the idea of making dango from scratch, but this recipe changed everything! The shiratama dango came together so quickly and really elevated my red bean soup. Love and will definitely make this again! #JOCcookingchallenge
Hi huagraphie! Wow! 🤩 Shiratama Dango Zenzai looks so delicious!
Thank you so much for trying Nami’s recipes, and sharing your passion for cooking with us! 💞
I made it! Had to buy everything off Amazon, to make it as authentic as I could. I think my water in the bean broth boiled away too much! But it was still great!
Hello, Lisa! Thank you for trying Nami’s recipe and sharing your photos! That looks delicious!
If you think the water has boiled off the next time, simply add more water and simmer for a little longer. As a result, you get wonderful soupy Zenzai.
We hope this was helpful!
I couldn’t find kirimochi in my local Asian supermarket, but I found a bag of frozen glutinous rice flour balls, which I’m guessing is pretty close to what you have in the recipe. My question is, after I boil them, do I still toast them?
Hi Diana! I think you found the Chinese glutinous rice balls Tang Yuan (汤圆). These are used after boiling them, and you won’t be able to toast them. It’ll be similar to Shiratama Dango, but these Chinese glutinous rice balls are softer and tender and less chewy like Japanese ones. 🙂
[…] Zenzai (Red Bean Mochi Soup) […]
Hi, I wanted to try this recipe but I couldn’t find Adzuki beans near me, could I substitute it with red kidney beans?
Hi Maria! Thank you very much for reading Nami’s post and trying her recipe!
If that is the case, sure you can try this recipe with red Kidney Beans. However, the bean’s flavor is slightly different, and you might want to adjust the sweetness for your taste.
We hope this helps!
What temperature do you recommend when using a regular oven? I have a toaster oven packed away (moving) and don’t want to burn the mochi
Hi Diana! Thank you very much for trying Nami’s recipe!
To bake Mochi in the oven, the temperature is recommended at 420F (215C).
We hope this works well for you!
Thank you so much for all the recipes! I already made a lot of yours recipes! Just did this and came out delicious! I was really afraid of doing this cause is really out of my confort zone but you explain so good that was a hit! I eat this when I went to Japan but even remenber or knew the name but thanks to One piece 😂 I found out the name and find your recipe! Also love the tsukemono!
Hi Juliana! Awesome! Thank you very much for trying Nami’s recipe and for your kind feedback!
We are so happy to hear you found Nami’s recipe and were able to create Zenzai at home!
We have 800+ classic & modern Japanese recipes on site, we hope you continue to enjoy many recipes! Happy Cooking!
Hi Nami, Are there recommendations on serving zensai to little kids, eg 3 or 5 years old? Would you cut mochi into 1cm cubes before toasting, or is it recommended not to serve them mochi because of the choking risk?
Thank you!
Hi Lisa, Thank you for reading Nami’s post!
In Japan, we start introducing Mochi after kids had developed the skill to eat around three years old. So they can chew it well and swallowed it well. As you mentioned, Mochi is a very sticky food and very high risk of choking. Please be careful!
Ensure that Mochi is small pieces like 1 cm and please keep an eye on kids while eating Mochi. If this is the first time to eat Mochi, you can introduce the Mochi separately without soup first so that kids will know how sticky it is.
We hope this helps!
Thank you for the guidance; it is helpful!
Could I use the leftover red bean soup to make red bean ice cream?
Hi Beck, If you simmer the red bean soup and turn it into the red bean paste, you can use it for making the ice cream. We hope this helps!
I made azuki an for daifuku mochi. Easy to follow recipe. I appreciated.
Hi Hisashi, Thank you very much for trying many of Nami’s recipe. We are so happy to hear you enjoyed it! Thank you for your kind feedback.
I don’t have any Anko (couldn’t find any). All I have is a can of crushed adzuki from Mitsuwa. Will this work? I just got some fresh mochi from Mitsuwa, but cannot stand how bland it is on its own, so I wanted to make this with it and my canned Adzuki.
Hi Savannah,
Yes, you can use a can of crushed adzuki by adding water and sugar to your taste.
We hope this helps!
Hello! I’m half Japanese and love Zenzai-but now with trying to be a little healthier- can I substitute the sugar for erythritol or other sweeteners? Will it take away from the traditional taste I love?
Hi Rina,
Thank you very much for trying this recipe!
We have never tried this recipe with erythritol and don’t know how the outcome will be. Sorry…
Let us know how it goes!
I have some freshly made omochi from my grandma and want to make this red bean soup. Can you tell me if the leftover soup can be frozen, or how long it will be good for in the fridge? I will make it in my instapot so can I reheat it on the stove top? Thank you!!
Hi Annette!
You are so lucky to have freshly made Omochi! It’s the best! 😋
You can transfer the red bean soup in an airtight container and store it in the refrigerator for up to 2-3 days or in the freezer for up to 1 month.
And yes. You can reheat it on the stovetop with low to medium heat.
Enjoy!
We followed the recipe exactly, and it came out delicious. However, next time, we’ll probably use even less sugar and let the instant pot cook the beans for a bit longer, since this time the beans were slightly undercooked for our personal taste.
Hi Angie!
Please feel free to adjust sweetness and cooking time for your liking!😉
Thank you very much for trying this recipe and for your kind feedback!
My mother is from Nemuro, at the easternmost point in Hokkaido, and even though our family lived in Tokyo when I was born, I never had ozoni for New Year’s growing up. We always had oshiruko. Thanks for posting this recipe and information, Nami! It’s rare these days in Denver, Colorado to find oshiruko in home or definitely any restaurants, so it’s nice to relive my childhood through your culinary expertise!
Hi Gil! I’m not sure if you can read Japanese, but this is an interesting map of Japan showing which location eat what type of Ozoni.
https://j-town.net/tokyo/research/results/198552.html?p=all
Blue: Clear soup (Kanto style Ozoni)
Red: Miso (Kansai-style Ozoni)
Orange: Zenzai / Oshiruko
Green: Others
My family lives in Kanto, but my grandma (my mom’s side family) is from Kyoto area so we eat white miso ozoni. 🙂
I hope you enjoy making Oshiruko at home. With azuki beans (pretty easy to access even at health store), you can make this at home! 🙂