Curry Indian soup with cajou nuts

1 leek, 1 apple, 1 banana, 1 tablespoon oil, 1 tablespoon butter, 1 tablespoon curry, salt, ground pepper, 1 teaspoon sugar, grated ginger, 500 ml vegetable soup, 50 g cashew nuts

Wash the leek and cut it in rings. Peel the apple and banana and cut them in cubes.
Heat the oil and the butter in a pot. Add the leeks, apple cubes and bananas and fry for 5 minutes. Season with curry, salt, pepper, sugar and ginger, mixing constantly.
Pour the vegetable broth and cook for another 15 minutes. Finally mix and season it. Roast the nuts and add them to the soup.