1.Place black bean in water until it becames soft, dry and grind into puree. Add in other ingredients for filling, set aside.
2.Combine all ingredients for bread then mix and knead for 20 minutes, until dough comes together in a lump. Place it in a box to ferment for 1 hour.
3.After fermentation, place dough on a table and punch it to redistribute air bubbles. Divide and cut it into 8 even pieces. Place it on the baking tray and cover with a damp cloth for 15 minutes.
4.Flatten it with a rolling stick and add in black bean filling. Knead it into a round shape and cover with a damp cloth for another hour for fermentation. Preheat oven at 170°C for 10 minutes and bake for 20 minutes.