Sugar-Free Koshian (Smooth Red Bean Paste) 無糖日式豆沙餡

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.
今天要跟大家分享的是製作和菓子時常會用到的紅豆沙餡，紅豆沙餡的傳統製作過程繁複，當中要經過清洗、去澀、慢火煮軟、去皮、沉澱、脫水、加糖熬煮等等工序，一點也不馬虎！此等功夫將紅豆的雜質通通都去掉，因此，豆沙味道十分清，口感亦相當細膩。傳統的日式豆沙在熬煮時會添入大量砂糖，以達到保濕和防腐的效果；可是，對於EC來說，這實在是太、太、太甜了，這次利用了赤藻糖醇加羅漢果糖的天然代糖做了無糖版本，另加了低聚糖糖漿幫助保濕，出來的效果也很滿意。其實，EC原想以代糖製作無糖版本脆皮紅豆糯米糕的，可惜的是，以赤藻糖醇做的糯米糕怎樣也烤不出脆皮效果，所以唯有只配合無糖內餡。

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.
若沒時間跟隨所有細節的話，大家可跳過讓豆沙慢慢沉澱至水變清澈的步驟，直接將豆沙脫水便可加糖或代糖熬煮。事實上，EC的陳皮豆沙餡、無糖廣式豆沙餡和無糖白豆沙餡就是這樣做的，有時懶惰起上來，甚至會把煮軟的紅豆扔進破壁機，打成細膩的紅豆蓉後直接倒在鍋中大火炒，大家大可依時間和心情決定用怎樣的製法。不做無糖版本的話，只要用回砂糖和粟膠就可以了。使用砂糖時建議份量可減大約一成，大約80克已經足夠。因為即使商品註明羅漢果糖跟砂糖是一樣甜，但EC仍覺得它不如砂糖般甜。至於保存方面，若放在雪櫃冷藏的話，EC建議最好在三、四日之內把豆沙用完，也可一次做較大的份量，然後把豆沙分成100至150克小份，用保鮮紙包好，然後放在密實袋中，放在冰格冷凍儲存，這樣子存放兩、三個月也沒問題的。用的時候只需提前一日放在雪櫃普通格，解凍後即可使用。

Sugar-Free Koshian (Smooth Red Bean Paste)
無糖日式豆沙餡

Makes about 500 g
成品約500克

Ingredients
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

材料
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
水 4湯匙
韓國低聚糖糖漿 2湯匙(40克)

Directions 做法

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.
紅豆洗凈後放進小鍋中，加進蓋過紅豆的水量，煮滾後加入一杯清水，再次煮滾後離火，把紅豆倒進大篩子內，以冷水沖洗後瀝乾，放回小鍋中加水重複以上步驟多煮兩至三次直至紅豆脹大，把紅豆倒出瀝乾，這做法可去掉紅豆內的雜質和帶有苦澀味的成份單寧。

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。
明火煮法：把瀝乾的紅豆放入鍋中加入蓋過豆的清水，煮滾後轉中小火煮60至90分鐘至豆身軟爛，中途要留意水量確保水份沒有煮乾，表面浮起的泡沫亦要撈走。

Mash the cooked bean with liquid inside with a ladle. Press the mashed beans through a fine mesh sieve to remove the skin.
用一個大的湯勺把紅豆連湯汁壓爛，過篩一次去除紅豆皮成軟滑紅豆泥。

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.
把紅豆泥轉放到大的鋼盆中，加入三至四杯飲用水拌勻，靜置半至一小時左右直至豆沙沉澱，倒去表面的水後用密篩過濾一次，重新加水拌勻並靜置讓豆沙沉澱，重複此過程三至四次左右，直至表面的水變得清澈為止，倒掉表面的清水，把豆沙用兩層白棉布或豆漿濾布包裹，用手大力擰出水份成脫水豆沙。

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.
平底不沾鍋鑊中放代糖和4湯匙水拌勻，煮滾之後加入脫水豆沙，中火翻炒至用刮刀劃過豆沙時會留下劃痕並且兩邊呈挺立狀便可離火，趁熱加入低聚糖糖漿拌勻，把豆沙轉移到淺碟中，完全放涼後用保鮮紙緊貼表面包好防乾，放進雪櫃保存並於三天內使用。