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:
Zenzai (Oshiruko) – Red Bean Soup with Mochi
Using Dried Azuki Beans (makes 4–6 bowls)
Using Store-bought or Homemade Red Bean Paste (Anko) (makes 1 bowl)
★ 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!
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.