Heat the oil in a large saucepan. Fry the onion cubes with the curry powder in them over medium heat for three minutes until translucent. Add the sweet potato, apple and stock. Bring to a boil, then turn down and simmer covered for 10 minutes.
Take the pot off the stove and puree the soup with the blender until smooth. Heat again and season with salt and pepper.
In addition: crispy white bread.
Important: Always sweat the curry powder so it doesn`t get bitter.