Mince the onion and microwave it in a heatproof container covered with plastic wrap at 600W for 40 seconds. Drain excess water and let it cool.

Mix the dough ingredients in a bowl until combined. Knead on a flat surface until smooth, then divide into 4 equal portions and shape into balls.

Combine the filling ingredients in a separate bowl and mix until sticky. Divide into 4 equal portions.

Roll out each dough ball into a 12cm circle. Place the filling in the center, fold the dough over the filling, and twist to seal. Repeat for all 4 buns.