First make the dumpling filling. Place a large frying pan over a high heat. Add the pork, breaking it up with a wooden spoon, and fry for 5 minutes, until golden. Remove from the pan and set aside to cool.
In a large bowl, combine the prawns with ¼ teaspoon of salt and mix until tacky and binding together. Add the rest of the filling ingredients and the pork, and mix to combine. Set aside while you make the dumpling skins.
In a separate bowl, mix the flour with 25g of the potato starch and 200ml of boiling water. Add the remaining potato starch and knead into a dough. Pull off 1 teaspoon of the dough, flatten it and, using a pastry knife or rolling pin, roll it on a lightly floured surface to form a circle, about 8cm in diameter.
Put 1 teaspoon of filling in the middle of the circle. Fold it into a half-moon shape, pushing one side into small pleats as you press the edges together to seal – this creates the classic ‘har kau’ shape.
To fold your dumplings into rabbits, gently press and elongate the sealed edge by about 2cm, then snip in half with scissors. Fold each side of them back and pinch so that they resemble bunny ears. Make two dimples in the front of the dumpling and add a black sesame seed or dab of food colouring into each one to make the eyes.
Set a steamer basket over a pan of boiling water. Put each dumpling on a square of baking paper, pop in the steamer, cover with the lid and cook for 8 minutes. Serve with soy and chilli sauces for dipping.