Cut pumpkin into slices, remove seeds and peel pumpkin. Dice 1 slice (approx. 150 g) finely, put aside. Cut remaining slices into large pieces. Peel and chop onions.
Peel 3 apples, quarter them, core them and cut them into large pieces. Heat 4 tablespoons of oil in a pot, fry onions, apple cubes and pumpkin pieces in it. Deglaze with stock, bring to the boil and simmer for about 20 minutes.
Quarter the rest of the apple, remove the core and cut into small cubes. Heat 1 tablespoon of oil in a frying pan. Fry the apple and pumpkin cubes for about 2 minutes until transparent, season with salt and pepper. Wash the coriander, dab dry, pluck leaves from the stalks, chop coarsely and fold into the apple-pumpkin cubes.
Mix the sour cream and cream until smooth. Stir the curry into the soup. Puree the soup and bring to the boil again. Season to taste with salt, pepper, sugar and vinegar. Arrange in soup bowls. Stir the sour cream mixture into streaks.
Sprinkle with pumpkin and apple cubes.