Ingredients:
50g natural starter
50g bread flour
50g plain flour
20g sugar
10g cocoa powder
40g water (i replaced the milk with water)
Method:
1. Mix all ingredient till dough form. Knead till shiny.
2. Let rest 15 mins. Roll flat and roll up like swiss roll. Rest another 15 mins.
3. Roll flat again and roll up like swiss roll.
4. I kept the dough in container and put in fridge overnight.
5. Bring out to room temp. Cut and steam in steamer for 10mins.
*Edited: point to note for own reference; do after step 3. Cut/shape into desired design, put on baking paper then only proof and steam.
Original link: https://icook.tw/recipes/122923
Also tested with green tea, plain with cranberries.