Unlike red bean paste -- the smooth, mashed filling found in mooncakes, steamed buns, and mochi -- this is a red bean topping similar to the azuki bean topping used over Korean patbingsoo. The beans are largely intact, boiled tender in water and sugar, and preserved with syrup. It can be used to flavor ice cream or to top shaved ice (or both!) —Cynthia Chen McTernan
about 1 1/2 cups
red beans or azuki beans
sugar (or more or less, according to taste)
Fully submerge the red beans in cold water. Make sure they're covered by at least an inch of water, then soak overnight.
Rinse the beans, then combine with two cups water in a small pot. Bring the water to a boil, then turn the heat to low and let simmer for about 1 1/2 hours, or until you can crush a bean easily between your fingers. You will need to add about 1/2 to 2/3 cup more water as it simmers down, but only add as much as is necessary to keep water just covering the beans. (I add about 1/3 cup at a time.)
When the beans are tender, add just enough water to cover the beans again, then add the sugar (to taste, so you may want less or more according to your preference) and stir until dissolved. Turn the heat to medium and bring to a rolling boil until the water forms a viscous syrup, about 10 to 15 minutes.
Remove the pot from the heat and let cool. Use the beans as a topping over shaved ice or ice cream, or use it to make your own red bean ice cream.