Finely grate the potatoes and pour off the resulting juice - you can still help a little with pressure, but make sure that the potato mixture stays nice and juicy. The onions are diced into small pieces - by hand, not with a grater or a mixer, and mixed with the potato mixture.
Season the potato onion mixture generously with salt and pepper (add nutmeg or rosemary to taste). Then finely dice the bacon, leaving a few larger slices and mix into the mixture together with the sliced sausages.
Put the whole thing in a heavy fire-proof saucepan (preferably cast iron) and place the bacon slices on top. Put in the oven for a good hour at 180 degrees.
If the mixture is not quite cooked afterwards or the crust is not really crispy and dark on top, then put it in the oven for a few more minutes (possibly with more heat or grill function at the end).
A green salad with yoghurt dressing or quark and a red from the Ahr go well with it.