Dice the onion and fry in oil until glassy. Add the cubes of pumpkin flesh and continue to fry for around 5 minutes. Peel and add the ginger root and deglaze with water. Cover and leave to cook for about another 15 minutes. Once it has reached the desired firmness, remove from the cooker, take out the root ginger and stir in the sour cream. Season to taste with curry powder, pepper and salt.
Tip: For those who do not like the floury consistency of pumpkin, remove the ginger and then use a hand-held blender to purée, adding a little water if necessary, until a pleasing consistency has been reached.