For the blood sausage ravioli on Riesling sauerkraut, prepare the pasta dough and knead firmly for at least 10 minutes. Wrap tightly in plastic wrap and let rest in the refrigerator for an hour.
In the meantime, heat the oil in a frying pan and sauté the finely chopped onion. Add garlic, black pudding and season with spices. Leave to cool.
Heat the lard in a saucepan and sauté the finely chopped onion. Add a pinch of sugar and pour in the wine. Add the sauerkraut and spices and simmer for at least half an hour.
Roll out the pasta dough and divide into two halves. Brush one half with egg white and place a heap of the black pudding on it at larger intervals. Make a well in the middle of the filling and put an egg yolk in it.
Now place the second half of the dough loosely on top and cut out the ravioli with a ring. Press the edges with a fork. Cook in salted water for about 4 minutes.
Arrange the blood sausage ravioli on Riesling sauerkraut and serve.