Thinly slice the spring onion, clove of garlic, chiles and banana.
Heat the oil in a pan and briefly fry the onion with the garlic and chilli. Pour coconut milk and vegetable stock, bring the soup to a boil and season with pepper, salt and sugar. Let the soup simmer for 5 minutes. Then add the bananas and puree the soup. Briefly heat the soup again and serve decorated with banana slices if necessary.