Jam-filled Germknödel

Method

1. Mix the flour with the salt and sugar in a large bowl. Mix the yeast with 2 tbsp of the warm milk and leave it for a few minutes until it starts to froth. Add this and the rest of the milk, the 35g melted butter and the eggs to the flour. Mix to form a soft dough.
2. Turn out onto a lightly floured surface and knead vigorously for 10 minutes (or with a dough hook in an electric mixer for 5 minutes). Put the dough back in the cleaned bowl and cover with a clean tea towel. Leave to rise somewhere warm for an hour or so until doubled in size.
3. Lightly grease a baking sheet. Knock back the dough, then divide into 10 equal pieces. Flatten each piece out on the work surface, then dollop a spoonful of the plum jam into the centre. Bring the dough around the jam and seal well by pinching the edges together with your fingers.
4. Put the parcels on the greased baking sheet, cover with the tea towel and leave to prove for 30-60 minutes or until doubled in size.
5. To make the sauce, heat the milk in a pan until almost boiling (it will be steaming). Whisk together the cornflour, egg yolks, sugar and vanilla in a bowl, then pour in the hot milk, whisking continuously. Return to the pan and put over a low heat. Cook, stirring, until it is lovely and thick. Add the melted butter and keep warm while you steam the buns.
6. Bring a very large half-filled pan of water to the boil. The traditional Austrian steaming method is to brush a clean cotton tea towel with melted butter, stretch it over the pan so that it droops a little but doesn’t touch the water, then secure with twine. Put the dumplings, a few at a time, in the tea towel and cover with the lid. (Or simply use a bamboo/ metal steamer lined with baking paper.) Steam the dumplings for about 10-15 minutes.
7. Brush with melted butter, then scatter with poppy seeds and sprinkle with icing sugar. Serve with the vanilla sauce.