How to Make Red Bean Cake with Horsegram Powder?

Ingredients:
Red beans 250 grams
4 cups boiling water
1/2 cup water
3/4 cup sugar
Tapioca starch as needed
2 tablespoons oil

Preparation:
1 Wash the red beans and soak them in cold water for 2 hours, then drain. Mix tapioca starch.
2 In a deep pot of 3 liters capacity, add red beans and 4 cups of boiling water. Cover and boil on high heat for 5 minutes until the water is boiling. Reduce to medium heat (70% power) and cook for 40 minutes, then increase to high heat for another 20 minutes. By now, there should be about 1 cup of liquid in the pot. The red beans will have released their juice; keep them for use.
3 In a large bowl, mix 1/2 cup water with the tapioca starch until smooth. Add 1 cup of boiling red bean juice to this mixture.
4 Add sugar and oil to the red beans, stir until dissolved, then slowly pour in the slurry while continuously stirring until well combined.

Method:
1 Pour red bean paste mugwort cake mixture into a greased long dish (21x11x6 cm), cover with plastic wrap, and seal the corners with aluminum foil, leaving the shiny side facing out.
2 Place the dish near the edge of the rotating tray, heat on high for 8 minutes. Transfer the dish by turning it 180 degrees to a new position and continue heating on medium (70% power) for another 7 minutes. Let it cool before cutting into portions for serving.