Wash, clean and slice the zucchini. Clean the mushrooms and rub with kitchen paper. Cut Lübzer dwarfs slightly several times. Cut all sausages in half. Put sausages, zucchini and mushrooms alternately on 8 skewers.
Wash the potatoes, peel them and cut them roughly into pieces. Cook in salted water for about 20 minutes. Heat the oil in a large frying pan. Fry the skewers on each side for about 3 minutes. Peel onions, cut into rings.
Keep skewers warm. Fry onion rings in hot frying fat until golden brown, keep warm. Heat 20 g butter in a saucepan, dust with flour and sauté while stirring. Add 200 ml milk and broth bit by bit while stirring.
Let simmer for 5 minutes at mild heat. Heat 200 ml milk. Drain the potatoes, add the milk and 20 g butter and mash everything to puree. Season to taste with salt and nutmeg. Season sauce with mustard, salt and pepper.
Wash the chives, dab dry, cut into rings and stir into the sauce. Serve skewers with sauce, mashed potatoes and onion rings.