Wash the potatoes and cook covered in water for about 20 minutes. Drain, rinse and peel. Let the potatoes cool down.
For the apple compote, peel, quarter, core and cut apples into pieces. Bring to the boil in a saucepan with sugar and apple juice, cover and simmer for about 10 minutes until the apples start to crumble.
Wash the marjoram, chop finely and stir into the compote. Season to taste with vinegar. Let it cool down.
For the Gröstl peel onions and garlic, dice finely. Cut potatoes into thick slices. Heat 2 tbsp. oil and 1 tbsp. butter in two pans. Divide the potatoes into the pans and fry them for about 10 minutes until golden brown, turning from time to time.
Dice roast beef. Add to the potatoes with onions and garlic. Fry for another 5 minutes. Season to taste with caraway seeds, salt and pepper. Add apple compote.