(1) Soak the peeled sweet potatoes in Alum water (dissolve 1tsp of Alum powder in 5 cups of water) for 1 hour. Rinse off the Alum and steam the sweet potatoes until soft. In a large bowl, mash the potatoes while hot. Add the sugar, salt and butter and mix well. Divide this mixture into two equal portions and put into separate containers.

(2) Dissolve the green tea powder in the hot water. Add this liquid to one of the portions of the mashed sweet potatoes and mix well.

(3) Line the bottom of a mold with plastic wrap, like saran wrap. Take the other portion of mashed sweet potatoes and press it with your hands into the bottom of this mold. Drain the red beans and gently rinse them with water. Spread them on top of the mixture in the mold. Then, add the green tea sweet mashed potato portion on top of the red beans and smooth out the surface.

(4) Cover the mold with a sheet of plastic wrap to prevent the mixture from drying. Cool in the fridge for 1-2 hours. When ready to serve, remove the plastic wrap on the top, turn the mold onto a plate, remove the mold and plastic wrap, and slice to serve. Enjoy~