Peel and wash the potatoes and cook them in boiling salted water for about 20 minutes. In the meantime, wash, peel and quarter the apples and cut out the core. Cut apples into cubes. Bring apple juice, lemon juice, sugar and vanilla sugar to the boil, add apple cubes and simmer for about 10 minutes at medium heat. Wash parsley, dab dry and chop finely.
Peel onions and cut into rings. Wash the bratwurst, dab dry, cut into slices and place on wooden skewers. Heat the oil in a pan and fry the sausage skewers for about 6 minutes, turning them over. Add the onion rings to the pan 2 minutes before the end of the frying time. Sprinkle sausage skewers with chopped parsley. In the meantime heat milk and fat. Drain the potatoes. Pour milk to the potatoes and mash them with a potato masher. Season with salt and nutmeg. Sprinkle mashed potatoes with onion rings.
In the meantime heat milk and fat. Drain the potatoes. Pour milk to the potatoes and mash them with a potato masher. Season with salt and nutmeg. Sprinkle mashed potatoes with onion rings. Arrange apple compote and sausage skewers on a plate. Serve garnished with parsley and apple slices