Blunzen (Austrian black pudding)

Instructions

1. Fry the thinly sliced onions in a pan until well browned. Cut the bacon into small cubes and render it separately.
2. Cook the groats in salted water, then drain and let cool slightly.
3. In a large bowl, mix the blood, groats, onions, bacon, marjoram, salt and pepper, then add the beaten egg.
4. Rinse the casing in lukewarm water, then fill it with the mixture, packing it gently and leaving a little room.
5. Tie off the ends and prick the sausage in several places to prevent it from bursting.
6. Poach the puddings in simmering water, without boiling, for 45 minutes, then serve hot with the mustard.