How We Make the Best Oshiruko (Red Bean Soup)

I still remember the first time we made Oshiruko together. It was a rainy Sunday afternoon, and we needed something warm, sweet, and soul-soothing. The aroma of simmering adzuki beans filled our kitchen, blending with the gentle hiss of the pot and the laughter echoing from the living room. Oshiruko is more than a dessert—it’s a nostalgic bowl of comfort that brings generations together around the table.

This traditional Japanese sweet red bean soup is surprisingly simple, yet profoundly satisfying. Served with grilled or toasted mochi, its silky texture and naturally sweet flavor create a deeply nurturing experience—especially during cold seasons. And the best part? There’s room to play. Whether we cook it slowly on the stove or speed it up with the Instant Pot, every version has its charm.

Let me take you step by step into our kitchen and share how we’ve perfected this lovely treat over the years.

Preparation Time

• Soaking the beans: 6–8 hours (overnight recommended)

• Cooking the beans (stovetop): 1.5 to 2 hours

• Using Instant Pot: 35–40 minutes

• Preparing mochi (grilled or pan-fried): 10–15 minutes

• Total time: About 2.5 hours (or 45 minutes if using Instant Pot)

Servings: 4
Difficulty: Easy

The Necessary Ingredients (Possible in All Kinds of Variations)

• 1 cup (200g) dried adzuki beans

• 4 cups water (plus extra for soaking and rinsing)

• ½ cup sugar (adjust to taste; we sometimes use a mix of white and brown)

• A pinch of salt

• 4 pieces of mochi (or shiratama dango as an alternative)

• Optional: A few drops of vanilla extract or yuzu zest for a twist

Vegan version: This recipe is naturally vegan as long as the mochi doesn’t contain hidden animal products (some processed types may).
Gluten-free version: Adzuki beans and mochi are naturally gluten-free, but check packaging to be sure.

Now that our ingredients are ready, it’s time to prepare the dish! There’s more than one way to cook this soup—each offering its own texture and charm.

The Steps of Preparation (Possible in All Kinds of Variations)

Some of us like the slow ritual of simmering beans gently on the stove. Others prefer the speed and reliability of an Instant Pot. Whichever method we choose, the result is always cozy and heartwarming.

Stovetop Method:

1. Rinse the adzuki beans well and soak them in plenty of water overnight.

2. Drain the beans and place them in a pot with enough water to cover. Bring to a boil for 5 minutes and then discard the water. This step helps reduce bitterness.

3. Add 4 cups of fresh water to the beans and bring to a boil again.

4. Reduce to a gentle simmer and cook uncovered for 1.5 to 2 hours, or until the beans are tender but not falling apart. Stir occasionally and add water if needed.

5. Add sugar and a pinch of salt. Simmer for another 10–15 minutes until the soup slightly thickens and becomes silky.

6. While the beans cook, grill or pan-fry the mochi pieces until puffed and golden. If using oven: 180°C (350°F) for 8–10 mins.

7. For a smoother soup, mash some of the beans or blend half the soup and return it to the pot.

8. Taste and adjust sweetness. Add a dash of vanilla or yuzu zest if desired.

9. Ladle the soup into bowls and top each with a grilled mochi. Serve hot.

Instant Pot Method:

1. Rinse and soak adzuki beans overnight (or for at least 4 hours if short on time).

2. Place the beans in the Instant Pot with 4 cups of water.

3. Set to Pressure Cook on High for 30–35 minutes.

4. Let the pressure release naturally for 10 minutes, then quick release the rest.

5. Open the lid, stir in the sugar and salt, and switch to Sauté mode.

6. Simmer for 10–15 minutes, mashing some beans to thicken the soup.

7. Meanwhile, prepare the mochi as described above.

8. Serve hot with mochi.

Nutritional Benefits

• Rich in plant-based protein
  Adzuki beans are a great source of protein, making this dish satisfying and filling.

• High in fiber
  Supports digestion, balances blood sugar, and leaves us feeling full longer.

• Natural antioxidants
  Adzuki beans contain polyphenols that help reduce inflammation and support heart health.

• Low in fat and cholesterol-free
  A gentle treat for those watching their fat intake.

• Contains iron, magnesium, and potassium
  These minerals support muscle function, energy, and heart health.

• Mochi provides energy-boosting complex carbs
  Perfect for a midday snack or post-meal comfort.

Possible Additions or Upgrades

There are many lovely ways to make this dish even more special:

• Add a drizzle of coconut milk for a richer, tropical flavor.

• Top with sweet chestnuts or yuzu peel for a traditional New Year’s touch.

• Use matcha mochi or kinako (roasted soybean flour) to add a new dimension.

• Swap sugar with maple syrup or honey (if not strictly vegan).

• Blend the entire soup for a smooth, creamy dessert-soup texture.

• Add a pinch of cinnamon or ginger for a spiced winter version.

Each variation brings new joy to the bowl—we love trying different versions throughout the seasons.

Frequently Asked Questions

Can I use canned adzuki beans?
Yes! Rinse them well and reduce cooking time. They’re a good shortcut but may be softer.

What is the difference between Oshiruko and Zenzai?
Oshiruko is smoother and more soup-like, while zenzai is chunkier with whole beans.

Can I freeze Oshiruko?
Yes, freeze without the mochi. Thaw and reheat gently on the stove.

Can I make it without mochi?
Certainly. Try using shiratama dango or just enjoy the soup as is.

Is it okay to eat Oshiruko cold?
Traditionally, it’s served warm, but some do enjoy it chilled in summer with shaved ice.

Can I sweeten with stevia or erythritol?
Yes, though it will slightly affect texture and depth. Adjust to taste.

Can I cook it in a slow cooker?
Absolutely. 6–7 hours on low after the pre-boil step works beautifully.

How do I keep mochi soft after cooking?
Serve immediately. Mochi hardens as it cools. Covering them helps retain moisture.

Is it a dessert or a meal?
Both! In Japan it’s a traditional winter dessert, but it’s filling enough for a light meal.

What does Oshiruko taste like?
Gently sweet, earthy, nutty, and warming. It’s unlike any Western dessert—soft, silky, soulful.