Today I’m sharing with you a recipe for Koshian, a smooth red bean paste that is used a lot for making wagashi.The traditional way of making Koshian is quite tedious. The red beans are rinsed, boiled briefly, cooked, mashed, and then deskinned. After that, the bean paste is soaked in water and let settle a few times until the water runs clear. The dehydrated sediment is then cooked with sugar to form a paste. Such sophisticated processes remove all the impurities within the red beans, resulting in the purest form of red bean with a very clean taste and silky smooth texture. Authentic red bean paste contains quite a lot of sugar for moisture retention and longer shelf life. It is way too sweet to my liking. I made mine with sweetener which is a blend of erythritol and monk fruit. I also added oligosaccharide syrup for moisture retention. At first, I was hoping to turn my Baked Coconut Sticky Rice Cake with Red Bean Paste (Nian Gao) into a sugar-free one; however, the skin didn’t turn out crispy as expected. So at the end I only use this sugar-free red bean paste as the filling.
If you don’t have time for such a detailed process (or simply don’t bother), go ahead without settling the mashed beans until the water runs clear and cook the dehydrated bean with sugar. In fact, this is how I made my Sweet Red Bean Paste with Chen Pi (Dried Mandarin Peel), Sugar-Free Sweet Red Bean Paste, as well as Sugar-Free White Bean Paste. Sometimes, I just get lazy and dump the cooked beans into my high-speed blender and puree the beans, and then scrape the puree into the pot and evaporate the moisture by high heat. You could decide how you want to make the bean paste depending on the time and gadget you have. For a non-sugar-free version, granulated sugar and white corn syrup would do. You may wanna further reduce the amount of sugar by maybe 10% as I found Lakanto slightly less sweet than granulated sugar (even if they say the sweetness level is 1 to 1). For storage, try to use the red bean paste within three to four days if stored in the fridge. Or you could make a bigger batch, divide the red bean paste into smaller individual portions (like 100 to 150 g), wrap each with plastic wrap and then store them in a freezer bag in the freezer for longer storage. They will store well in the freezer for 2 to 3 months without any issue. Just thaw them in the fridge overnight and it will be good to use.
Sugar-Free Koshian (Smooth Red Bean Paste)
Makes about 500 g
200 g red beans (I used organic red beans)
90 g erythritol/monk fruit blend sugar substitute (I used Lakanto Classic)
4 Tbsp water
2 Tbsp (40 g）Korean oligosaccharide syrup
紅豆 200克 (EC用有機紅豆)
赤藻醣醇/ 羅漢果糖混合天然代糖(EC用Lakanto Classic) 90克
Place rinsed red beans in a pot. Fill pot with enough water to cover the beans. Bring water to a boil then add another cup of water. Remove from heat when water comes to a full boil again. Discard water and rinse beans in a strainer under running water. Drain and place beans back into the pot, add water and repeat this cooking process two to three more times until the beans swell up. Drain well. This step removes the unpleasant and bitter aftertaste of the red beans by minimising the contents of tannin.
Electric pressure cooker (Instant Pot) method: place drained beans in the inner pot of Instant Pot and fill with enough water so that the beans are covered by an inch of water. Close the lid and turn the steam release handle to sealing position. Press the “bean” button once or press “manual/pressure cook” and adjust to cook at high pressure for 30 minutes. When the timer beeps, press “cancel” and let pressure release naturally (about 10 minutes). Carefully remove the lid.
Stove top method: place drained beans in a pot and add enough water to cover the beans. Bring to a boil then simmer over medium-low heat until beans are tender, about 1 to 1.5 hour. Check water level occasionally to make sure the beans are always covered in water. Skim off any foam that floats on top during the cooking process.
電子壓力鍋(Instant Pot)煮法：把瀝乾的紅豆放入Instant Pot內鍋，注入蓋過豆約一寸的清水，關上鍋蓋把排氣閥調整到密封“sealing”位置，按”bean”鍵或按“manual/pressure cook” 鍵選擇高壓煮30分鐘，煮好後按“cancel”等待自然放壓(約10分鐘)，小心打開蓋子。
Mash the cooked bean with liquid inside with a ladle. Press the mashed beans through a fine mesh sieve to remove the skin.
Transfer strained bean paste into a large mixing bowl. Add 3 to 4 cups of drinking water and mix thoroughly. Let the mixture sit at room temperature for half to 1 hour or until the bean paste has settled. Carefully discard the water on the surface and strain mixture with a fine mesh sieve. Add water again and let mixture settle. Repeat this process 3 to 4 times until the water on the surface becomes clear. Line a large bowl with a nut milk bag and pour the red bean sediment inside. Wring out excess liquid and collect the strained red bean paste.
In a large nonstick pan, melt sugar substitute with 4 tablespoons of water. When mixture starts to boil, add strained bean paste and cook over medium heat with constant stirring until mixture leaves a trail with pointy edges while a spatula is run through it. Remove from heat and stir in the oligo syrup until blended. Transfer the bean paste to a shallow plate or container and let cool completely. Press a plastic wrap directly against the surface. Store read bean paste in the fridge and use within three days.
I used this for my sticky rice cake.
Korean Oligo syrup used in this recipe
Erythritol/monk fruit blend sugar substitute