Wash 1 potato and cook covered in salted water for about 20 minutes. Steam Brussel sprouts in little boiling salted water covered about 15 minutes.
Brush a small coated pan with oil. Fry the ham in it until crispy and take it out. Fry the sausages in hot frying fat all around for about 5 minutes.
In the meantime cut the onion into fine rings. Add to the sausages in the pan and fry until brown.
Drain the potatoes and add milk. Mash everything with a potato masher. Season to taste with salt and nutmeg.
Drain the Brussels sprouts well and mix them with the ham cubes. Arrange sausages, mashed potatoes and sprouts. Sprinkle with onion rings.