For the meatballs soak rolls in cold water. Peel and finely dice the onions. Knead minced meat, egg, approx. 1/3 of the onions, mustard, squeezed out roll, 1 1/4 tsp salt and 1 tsp pepper well.
From the chopping mass, form balls the size of golf balls. Put them in a cold place.
Peel and wash the potatoes, cut them in half depending on their size and cook in boiling salted water for about 25 minutes. In the meantime clean and wash the mushrooms, halve them according to size. Heat 2-3 tablespoons of oil in a large pan.
Fry the meatballs for about 8 minutes while turning.
In the meantime clean and wash the salad, pluck into bite-sized pieces and drain well. Mix lemon juice, sugar, about 1/2 of the remaining onions, salt and pepper. Fold in 3 tablespoons of oil. Mix salad and vinaigrette.
Remove the meatballs from the pan.
Add the mushrooms to the frying fat and fry while turning. Add remaining onions and fry briefly. Season with salt and pepper. Add 20 g butter and melt. Dust with flour, sweat on and gradually deglaze with stock and cream while stirring, bring to the boil and simmer for about 1 minute.
Add meatballs and warm up.
Bring milk and 50 g butter to the boil in a small pot. Wash parsley, shake dry and chop finely. Drain the potatoes, add the milk and butter mixture and mash coarsely with a potato masher.
Season to taste with salt and nutmeg.
Arrange meatballs in mushroom cream and mashed potatoes on plates, sprinkle with parsley. Arrange salad in small bowls, garnish with lemon slices if desired. Serve with jellied cranberries.