Peel and finely chop the onion. Peel ginger and chop finely. Clean and wash the chillies, cut them in half lengthwise, remove the seeds and chop very finely. Cut the ends off the lemon grass. Cut the stalks slightly lengthwise so that the outer hard leaves can be easily removed.
Press lemongrass sticks slightly flat. Wash the pumpkin, cut in half and remove the seeds with a tablespoon. Then cut the pumpkin and its skin into small pieces of about 2 cm.
Heat the oil in a large pot. Fry the onion, ginger, chilli and lemongrass in it. Stir in pumpkin and fry briefly. Add 400 ml water and coconut milk. Stir in stock. Bring everything to the boil, cover and simmer for about 10 minutes.
Roast peanuts in a pan without fat. While doing so, always swing the pan back and forth so that the nuts do not burn. And be careful, the browning goes really fast. Take out the peanuts and chop them coarsely.
Remove lemongrass from the soup. Finely puree the soup with a hand blender. Season to taste with salt, pepper, sugar and lime juice. Wash the coriander, shake dry and remove the leaves. Serve the soup with peanuts and coriander (only if you like!).