1: Begin by preparing the prawns for the dumpling filling. Fill a bowl with cold water and put the prawns in to soak, leaving for 30 minutes to firm up
2: Drain the prawns, then transfer them to a blender and blend until smooth. Add the stock cube, flour, pepper, salt, sugar and oil to the prawn paste, stir to combine and reserve in the freezer for 2 hours
3: To make the dough, sieve both the wheat flour and potato flour into a large mixing bowl. Gradually add in the hot water, stirring the mixture with a palette knife. Once all the water has been added use your hands to lightly knead the mixture until you have a smooth ball of dough
4: Divide the dough into individual balls, taking into consideration that there will be more dough than is needed for the filling. Freeze any excess dough and, on a lightly floured surface, roll out the balls into 6mm thick discs
5: To assemble the har gau place a dough disc in the palm of your hand and spoon one level tablespoon of the har gau filling into the centre of the round. Using your index fingers and thumbs, mould the dough upwards around the filling and pinch it together into a shell shape
6: Place the har gau in a steamer basket and steam for 3–6 minutes. Remove from the steamer and serve immediately