
Prepare the beans Rinse the red beans several times in cold water, then place them in a bowl and cover with enough warm water to fully submerge. Soak for about 12 hours, or overnight.
First boil Drain the soaked beans and place them in a pot with about 2 cups (500 ml) of fresh water. Bring the beans to a boil, then simmer for 2-3 minutes and drain. This quick blanch helps remove the earthy taste from the beans and makes the final paste taste cleaner.
Second boil Return the beans to the pot with 2 cups (500 ml) of fresh water. Bring to a boil over high heat, then lower the heat to medium and simmer. As the beans soften, reduce the heat again to medium-low and continue cooking until they are fully tender, about 30 to 40 minutes.
Blend the beans Once the beans are cooked through, drain them but reserve about 1/3 cup (80 ml) of the cooking water. Transfer the beans to a blender, add the reserved water, and blend until smooth and velvety. You shouldn’t notice any bean skins or texture at this point.
Sweeten and thicken Pour the blended beans back into a clean pot. Add the sugars, salt, and rice syrup or golden syrup. Cook over medium to medium-low heat, stirring constantly to prevent sticking, until the paste thickens, about 10 minutes. Adjust the cooking time depending on your preferred consistency. For use as a filling in Korean rice cakes, the paste should be thick yet pliable so it can hold its shape. It should look like soft mashed potatoes when ready.
Finish Let the red bean paste cool a bit before you use it in your favorite Korean desserts. While it’s warm, it’s soft and silky; as it cools, it’ll firm up a little more.