Clean and wash the potatoes, carrots and leeks. Slice the leek and carrots and cut the potatoes into cubes. Heat the fat in a pot. Sauté the vegetables in it and deglaze with broth.
Cover and cook for ten minutes. Meanwhile drain the tomatoes and collect the juice. Cut the tomatoes into bite-sized pieces. Squeeze oranges. Add orange juice, tomato pieces and juice to the vegetables.
Season with cayenne pepper and simmer for another five minutes. Season soup again with salt and cayenne pepper.