Anko is an essential ingredient for Japanese traditional sweets. All you need to do is simmer it so it's easy to make. Great with yogurt or topped on cheese toast.
Every New Year, I make adzuki. It might not be the New Year season now, but I received a lot of adzuki beans from my parents, so I made plenty of tsubu-an.
Be sure to cook the beans until they are tender before you add the sugar. The beans will not soften after you add the sugar.If you make a large batch, it will be convenient if you divide the tsubu-an into small portions, wrap them up tightly with plastic wrap, store in a Ziploc bag or other containers and freeze them.
Enjoy Japanese food around the world.