1. In a bowl add all the bread dough ingredients. Knead the dough until it becomes elastic and smooth. Lightly coat the bottom of the bowl with oil and place the dough. Cover it with cling film and put it in a warm place for about 1 hour or until the dough doubles in volume.
Prepare the filling
1. Meanwhile, let's prepare the filling. In a skillet, heat 1 tbsp vegetable oil and fry garlic until fragrant. Add zha cai, onion, stir-fry until wilted, stirring continuously. Remove from the heat and let it cool to room temperature.
2. Transfer this onion mixture into a bowl. Add the ground beef and knead the mixture well until well combined and sticky. Set aside.
Put it all together
3. Divide the dough into 15 equal size balls. Lay them across a lightly flour dusted surface. Cover with cling film and let them sit for about 15 mins.
4. Flatten each ball with your hand and roll with rolling pin into about 10 cm in diameter with thin edges. Place the filling in the middle of each of the dough.
5. Wrap and pleat the dough up to seal on the top. Repeat and finish all the buns in this way.
6. Arrange the buns on individually cut baking papers in your steamer. Leave about 3cm space between buns (See pictures - the buns will get bigger while being steamed). Steam for about 15 mins.
7. Remove buns from steamer and serve hot with tonkatsu or chuno sauce!