Peel, wash and coarsely dice the potatoes. Clean, wash and finely chop spring onions. Fry potatoes and 2/3 onions in hot fat. Add a good 1 l water, marjoram and stock, bring to the boil. Simmer for about 15 minutes.
Finely dice the roast beef and mix with half of the remaining onions. Roast the bread one after the other in a toaster until golden brown. Spread the roast beef tartar and about 1 teaspoon crème fraiche on each. Season with pepper
Finely puree the soup. Season to taste with horseradish and salt. Arrange the soup and stir in some crème fraîche. Sprinkle with the rest of the onions and some pepper. Serve immediately with the bread chips