Mash the peeled and boiled boiled potatoes, whisk the heated milk, butter, salt and a pinch of nutmeg with a whisk. Season the peeled, pitted and quartered apples with sugar and lemon juice and boil in a little water until soft, coarsely mash and mix with the mashed potatoes.
Cut the shallots into strips and roast them until golden. Cut the peeled black pudding into finger-thick slices, turn lightly in flour and fry in a little lard on both sides until crispy.
Spread the puree on the plates, place black pudding on each one and spread the roasted onions on top.