Prepare the dough: activate the yeast, then mix flour, yeast mixture, sugar, baking powder and butter and knead for about 15 minutes until it doesn't feel incredibly sticky anymore. Add more water if you need.

When you've got a nice dough let if proof for half an hour (or longer) in a warm place. Alternatively let it proof in the fridge over night, you want the dough to have nearly doubled in size.

Peel and chop the sweet potato into even cubes. Steam for 20 minutes, then mash into a paste. Add some water and if you want a sweeter filling add sugar.

Take the dough and cut it into 8 equal pieces. Make a ball out of each piece of dough, flatten them and roll them into circles (not too thin!!)

One by one put a flat dough circle onto your hand and place a potato ball in the middle of it. Seal the dumplings, trying to keep the filling central. The side with the seal will be the dumpling's bottom.

Place each sealed dumpling on a piece of baking paper and cut a little cross on the top so the filling shines through.

Let the sealed dumplings proof for another 10-15 minutes and then steam them for 15 minutes.