Thai-style pumpkin soup

Ingredients

• 60 gram butter, chopped
• 1 onion, chopped
• 1 tablespoon grated ginger
• 2 clove garlic, crushed
• 600 gram pumpkin, peeled, chopped
• 3 cup chicken stock
• 1 lemongrass stem, bruised
• 1 small red chilli, finely chopped
• 2 coriander roots, washed, chopped
• 400 millilitre can coconut milk
• 100 gram rice stick noodles
• fish sauce, brown sugar, to taste (about 1-2 tablespoons of each)
• beansprouts, sliced red chilli, coriander leaves, to serve