Step 1

Gather all the ingredients.

Step 2

Rinse azuki beans and discard broken ones.

Step 3

Transfer the drained azuki beans to a large pot. Add water till 1-2 inches above azuki beans. Turn the heat on high.

Step 4

Bring the water to boil over medium high heat.

Step 5

Once boiling, discard the water and put the azuki beans back into the same pot.

Step 6

Add water till 1-2 inches above azuki beans.

Step 7

Bring the water to a boil over medium-high heat. Once boiling, put an otoshibuta (drop lid) over the azuki beans (Otoshibuta will prevent the beans from dancing around too much). Turn down the heat to medium-low and keep it simmering for the next 1 to 1.5 hours.

Step 8

Water will evaporate so you need to keep adding water so the beans are submerged. After 1 hour, pick one bean and mash it with your fingers. If it is mashed easily, it's done.

Step 9

Drain the azuki beans over a sieve.

Step 10

Put the beans in the same pot. Turn the heat to medium-low heat and add half of the sugar.

Step 11

Mix well with the azuki beans. Once sugar is dissolved, add the rest of the sugar.

Step 12

Mix, stirring constantly and add the salt.

Step 13

If you plan to use red bean for Zenzai (Oshiruko), you can use it right away. If you prefer a thicker version, reduce the soup.

Step 14

Let the moisture evaporate. When you can draw a line on the bottom of the pot, turn off the heat. Don't worry if it's still loose; Anko will continue to thicken as it cools. Transfer to a flat baking sheet to let cool completely. Tsubuan is ready to use. Scroll down to see how to store it.

Step 15

Drain the azuki beans over a sieve, reserving some cooking liquid.

Step 16

Transfer the beans to a food processor. Add 1-2 Tbsp cooking liquid if necessary and run the food processor until the beans become a fine paste.

Step 17

Transfer the fine paste back into the same pot. Turn the heat to medium-low heat and add half of the sugar.

Step 18

Mix well with the bean paste. Once sugar is dissolved, add the rest of the sugar.

Step 19

Let the moisture evaporate, stirring constantly. Add the salt.

Step 20

When you can draw a line on the bottom of the pot, turn off the heat. Don't worry if it's still loose; Anko will continue to thicken as it cools. Transfer to a flat baking sheet to let cool completely. Koshian is ready to use.

Step 21

If you're not using the red bean paste right away, you can transfer the red bean paste in an airtight container and store in the refrigerator for up to 3-4 days or in the freezer for up to 2 months. You can also divide and wrap 100 g of red bean paste in a plastic wrap and store it in a freezer bag. When you’re ready to use, you can defrost in the refrigerator overnight. Tip: Compared to store-bought red bean paste, the amount of sugar used for homemade Anko is not enough to keep for a long time.