These sweet steamed buns are a German speciality and should have a caramelised bottom and soft pillowy tops.
Tip the flour into a large mixing bowl. Add the sugar to one side of the bowl and the yeast to the other. Add the milk, eggs and butter and turn the mixture round with your fingers, until you’ve picked up all the flour from the sides of the bowl. Use the mixture to clean the insides of the bowl and continue until the mixture forms a rough dough.
Tip the dough onto a lightly floured work surface and knead for 5–10 minutes. Work through the initial wet stage until the dough starts to form a soft, smooth skin. Scatter the lemon zest on top of the dough and knead until evenly incorporated.
Place dough in a lightly oiled bowl, cover with cling film and leave to rise for at least 1 hour until doubled in size.
For the plum sauce, roughly chop the plums, discarding the stones. Tip the plums into a pan with the orange juice. Sprinkle over the sugar and cook over a low heat until the sugar dissolves.
Increase the heat and boil for 10 minutes, mashing the plums with a wooden spoon until thickened. Remove from the heat and add the cinnamon. Leave to cool slightly then blend to a thick sauce. Set aside.
For the vanilla sauce, heat the milk and cream in a saucepan over a medium heat to just below boiling point. In a large bowl, whisk the egg yolks, vanilla paste, flour and caster sugar together until pale and fluffy. Pour over the warmed milk, whisking continuously. Pour the mixture into a heavy-based pan and cook over a very low heat for 3–4 minutes stirring continuously until smooth and thick enough to coat the back of a spoon. Remove from the heat and set aside. Cover the surface of the sauce with cling film, to prevent a skin forming.
Turn the risen dough onto a lightly floured surface. Turn inwards repeatedly until all the air is knocked out. Divide the dough into 12 pieces and roll into balls.
For the poaching liquid, heat the butter, milk and sugar in a large heavy-based saucepan (with a tight-fitting lid) over a medium heat for 5 minutes until the sugar dissolves. Remove from the heat and add the dough balls, ensuring all are sitting on the base of pan, then leave to stand for 15 minutes until doubled in size.
Return the pan to a low–medium heat and cook, covered with a lid, for 25–30 minutes. Remove the lid and cook for a further 5–10 minutes until the bases are golden and caramelised.
Remove from the heat and carefully remove the dampfnudel from the pan. Serve with the plum and vanilla sauce.