Above buns is bake with 13.5inch x 9inch cake tin/pan, resulting fat and short buns. Best recommended cake tin is 12inch x 8 inch size!
1. Steam or boil sweet potatoes until it if fully cooked. Use folk to check whether the folk can easily get through the sweet potatoes to determine the entire sweet potato is fully cooked.
2. Wipe dry the water on the sweet potatoes skin, leave it cool before peeling it's skin. Smashed the sweet potatoes evenly with folk after skin removed.
3. Add in all ingredients except butter into mixing bowl and mixed until well combined. Wrap the bowl with cling film for 30mins( Autolyze process).
4. After 30mins, add in butter and knead until well combined( Kitchenaid speed 2).
6. Using medium speed( kitchenaid mixer speed 4) to knead the dough until window pane formed. Scrap the dough at least once after few minutes. It took me around 8 mins to achieve window pane.
7. Stop the mixer, let the dough rest for 10mins to relax the it. I skip bulk fermentation on this bun as I noticed that there is no texture different without bulk fermentation.
8. After 10mins, transfer the dough onto lightly dust(flour) wood panel. Sprinkle some flour on the dough. shape it to round shape and cut them into 12 small balls.
9. Let the dough balls rest for 5-10mins, shape them and align them into greased cake tin. Wrap the tins with cling film and set aside for final proofing.
10. Let the dough ball achieve size about 2-3x of its original size, it took me ~8hours room temperature to achieve the ready to bake size.
11. Brush the bun surface with egg wash, sprinkle some sesame and transfer the tin into preheat oven(180-200 degree Celcius). Bake until the buns surface turn golden, about 10-15mins.
12. Transfer the buns to wire rack after remove the cake tins from oven. Let it cool and it is ready to serve.