There are two types of An (sweet bean paste) in Japan. They are called Kuroan and Shiroan. They are classified by their colour, so kuroan is black and shiroan is white. However kuroan is much more of a red than black, but anyway.
Kuroan is made from Azuki beans. There are also two types of Kuroan: tsubu and koshi. These are the two different textures that the An can be. With tsubuan, the azuki beans are not hulled so the texture is not smooth. On the other hand, Koshian is strained and pureed so it is much smoother. Kuroan is widely used for making Wagashi, which are Japanese sweets, and you can buy them ready made in tins both in Japan and outside of Japan.
Shiroan is not so commonly sold in Australia and not even in Japan. But the type of Strawberry Daifuku that I used to eat use Shiroan, not Kuroan. So I am going to share a Shiroan recipe. Shiroan is more delicate than kuroan I think. Shiroan is always hulled, strained, and pureed. It is very simple to make but it just takes a little bit of time. So if you are going to make some Wagashi and need An, you need to make it ahead of time.
A recipe for sweet white bean paste which is used for many Japanese sweets and desserts
Soak the white kidney beans in water over night.
Drain the water and hull the beans.
Place the hulled beans in a saucepan and cover with water and cook for about 1 hour and 30 minutes or until the beans become soft.
Drain the water and beat the cooked beans with a hand held electric mixer.
Add sugar and a pinch of salt and stir constantly over low heat till the paste texture becomes a little bit thicker. It will become firmer when it has cooled down.
cooking time does not include soaking beans time over night