Homemade Koshian (Smooth Sweet Red Bean Paste)

Steps

1. 1

   Place the dry adzuki beans in a bowl and add enough water to cover them completely. Swirl the beans around, drain, and repeat the washing process 2–3 times.

2. 2

   Transfer the washed beans to a pot and add fresh water until the beans are submerged, with the water level about 1–2 inches above the beans. Bring to a boil over medium heat and cook for 10 minutes.

   Start 10-minute timer
3. 3

   Drain the beans and discard the cooking water.

4. 4

   Rinse the pot, return the beans to it, and add fresh water so the beans are fully submerged and the water stands 1–2 inches above them.

5. 5

   Bring the water to a boil over medium heat. Scoop off and discard any foam that forms on the surface.

6. 6

   Once boiling, reduce the heat slightly, place a drop lid over the beans, and gently boil until they are fully softened, usually 40 minutes to 1 hour. Check occasionally, stir the beans, and add more water as needed to keep them submerged.

   Start 40-minute timer
7. 7

   After about 40 minutes, remove several of the larger beans and run them under cold water until cool enough to handle. Press each bean between your thumb and forefinger. The beans are ready when they spread like a soft, smooth paste; if they remain hard or grainy, continue cooking and test every 5–10 minutes until soft to the core.

   Start 40-minute timer
8. 8

   Turn off the heat. Place a fine-mesh sieve over a heatproof bowl and pour the cooked beans into the sieve.

9. 9

   Crush the beans thoroughly, pressing them through the sieve as you work. A pestle can be used to grind them. Pour water over the beans occasionally to loosen the interiors from the skins.

10. 10

    Scrape the underside of the sieve into the bowl to collect the bean paste, then fill the bowl with fresh water. For an even smoother texture, optionally blitz the mixture in a food processor and return it to the bowl.

11. 11

    Let the mixture stand for 5–10 minutes, until the paste settles at the bottom. Carefully pour off the surface water without losing the paste, refill the bowl with fresh water, and repeat this process three times in total.

    Start 10-minute timer
12. 12

    Pour the bean paste into a cheesecloth and squeeze out all of the water. Set the drained paste aside.

13. 13

    Put the sugar and 2–3 tablespoons of water in a saucepan. Heat over medium-low heat, stirring continuously until the sugar has dissolved.

14. 14

    Add the drained red bean paste to the dissolved sugar. Stir continuously over the heat until you can draw a line across the bottom of the pan. Do not overcook the mixture, because it will firm as it cools.

15. 15

    Turn off the heat and stir in the salt.

16. 16

    Transfer the koshian to a wide container and press plastic wrap directly onto its surface to prevent drying. Leave it to cool to room temperature, then cover the container with a lid and refrigerate for up to 3 days. Alternatively, divide it into portions and freeze for up to 1 month.

17. 17

    Use the homemade koshian as a filling for Japanese desserts such as mochi, daifuku, dorayaki, anpan, and manju.