Heat up the milk to a lukewarm temperature. Mix in the yeast and sugar and stir. Leave to rest in a warm place for 10 minutes. You should see some bubbles forming on the surface. This means your yeast is activating. If you cannot see them your milk might have been too hot, and you should start again.
125 ml milk, 7 g instant yeast, 40 g sugar
Preheat your oven to its lowest setting.
Now add in the flour, salt, vanilla sugar, butter, lemon peel and egg yolks. Knead the dough with a hand or stand mixer, with a dough hook to a smooth dough for approximately 10 minutes.
250 g flour, 2 egg yolks, 1 teaspoon vanilla extract, 1 teaspoon grated lemon peel, 50 g butter, 1 pinch salt
Cover the bowl with a damp tea towel. Turn off the oven, and place the bowl in it. Leave to rise for about 45 minutes. By this time the dough should have doubled in size.
Knead the dough for about 2 minutes by hand on a floured surface to remove any air bubbled that might have formed during the rise. Then divide the dough into four equal portions. Sometimes it helps to use a kitchen scale if you want to be exact.
If you want to use the rum, mix it in with the plum butter. Flatten the dough pieces by hand, and add a tablespoon of plum butter/ jam in the middle. Fold the sides to the middle and form into a round ball.
4 tablespoon plum butter, 1 teaspoon rum
Leave the balls to rise for a further 15 minutes. The seams should be at the bottom.
In the meantime, grease the bottom of your steaming basket with butter, so the dumplings do not end up sticking to the pan.
Pour water in a pan and bring to boil. It is important that the water does not widley bubble, just simmer. Otherwise the water might spit and you the bottom of your Germknödel will get soggy.
Depending on the size of your steamer basket, place the dumpling inside. You might have to steam them individually. They should not touch and need enough space between one another. The dumplings will expand and then they might stick together if you are not careful. Steam for approximately 15 minutes.