For taro wrapper dough:

Cut yam into medium pieces. Arrange loosely in a steamer, steam till cooked through. Remove from steamer and mash while it’s still hot. Set aside.

In a bowl, stir 3/4 cup of boiling water into wheat starch with a fork to form a rough dough. When the temperature is still hot but touchable by hand, combine the dough with mashed yam

Then add butter, baking soda, salt and sugar. Fold in and knead completely. If you find any lumps, take them out.

Knead the dough into a ball and refrigerate for 1 hour.

For the char siu filling:

Cut the pork neck into cube size. Peel and devein the prawns and chop roughly. Combine the marinate and sauce ingredients. Add the marinate to the pork and prawns mixture and refrigerate for 15 minutes.

Remove the filling from the stove, transfer to a bowl and refrigerate for 2 hours until fully chilled.

Pinch the dumping closed and mold into a shape an egg. Repeat until 12 dumplings are complete, then refrigerate for 1 hour.

Prepare flour, egg and bread crumb or panko bread crumb.
Crumb all the 12 dumplings. Refrigerate again for 1 hour.

Heat oil to 180 degrees. Deep fry the dumplings in batches for 2 - 3 minutes.

Serve immediately.