Prepare water and butter dough (separately). Mix all ingredients into dough then rest them for 20 minutes in room temperature

Divide water and butter dough into 20 equal portions.

Flatten water dough. Then, place a portion of butter dough on the centre of flattened water dough, and wrap water dough around the butter dough. Seal the edges.

Flatten the combined dough, then roll it into long strip.

Slightly flatten the dough, then roll it up like Swiss roll. Then flatten it once again.

Place red bean filling in the centre of the dough, then wrap it, and shape it. (either rounded ball, or into flat round disc)

Repeat the shaping steps until complete.

Brush with egg wash (whole an egg + 2tbs plain water or milk) (I added yellow food colouring into the egg wash). Bake it in the preheated oven at 180°c @ 350F for about 20-25 minutes.