Red bean paste, or Koshian (こしあん), is one of those simple yet deeply comforting staples in Japanese sweets. Unlike its chunkier counterpart Tsubuan (つぶあん), which retains whole azuki beans, Koshian is silky smooth and velvety, making it perfect for delicate pastries, mochi, and anko-filled breads.

Soaked overnight...
The process is simple—just slow-cooked azuki beans, sugar, and a pinch of salt—but the result is something truly special. There's a deep, natural sweetness from the beans, balanced by just the right amount of seasoning, making it versatile for both traditional and modern treats.

Mash to your desired consistency...
Koshian has a long history in Japanese cuisine, dating back centuries to when red beans were first introduced to Japan from China. Over time, the process of refining azuki beans into a fine, smooth paste became a hallmark of wagashi (traditional Japanese sweets). You’ll often find Koshian inside dorayaki, taiyaki, manju, and even delicate yokan.
But for me, one of the simplest and most satisfying ways to enjoy it is as an Ogura Toast—a thick slice of buttered toast generously spread with red bean paste, a specialty of Nagoya. The combination of the sweet bean paste and salty, melty butter is pure comfort.

Ogura Toast...
If you’ve never made red bean paste at home, this is your sign to give it a try. It requires just three ingredients and a bit of patience, but the reward is a homemade spread that’s leagues better than store-bought versions.
Whether you use it in desserts, pair it with toast, or even mix it into lattes, Koshian is a must-have for anyone who loves Japanese flavors. Give it a go—you might just find yourself making it again and again!

Ingredients:
Good Quality Azuki Beans, 150g
Granulated Sugar, 100g
Sea Salt, Pinch
Equipment:
Heavy Sauce Pot
Directions:
Soak the red beans with water in a large bowl overnight.
Make sure the red beans are fully submerged.
The next day, drain and discard the soaking liquid.
Transfer the beans to a heavy sauce pot.
Add just enuff water to fully submerge the beans.
Bring it up to a simmer over medium heat.
Cover and cook for about an hr or until the beans are soft, or can easily be squashed by your fingers.
Stir occasionally to prevent burning.
Add just enuff hot water to fully submerge the beans if necessary.
Once the beans are soft, add in sugar and salt.
Stir to combine well and until the sugar has completely dissolved.
Taste and adjust for seasoning with sugar.
Continue stirring and cooking until the liquid has almost evaporated.
Remove from heat and transfer to a large mixing bowl.
Mash with a fork to your desired consistency, or you can use a stick blender.
I like to spread the koshian on some toast and top it with salted butter to make an Ogura Toast.

Simply yummilicious...

The combination of sweet, savory and buttery...
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