Heat oil. Add chopped onion and garlic and sauté until soft and the fumes coming off lose their acridity. Add the chillies and cook for a minute or so. Add the sweet potato, carrots and butternut and cook for 8 minutes, stirring occasionally. Add stock. Cover and bring to the boil. Simmer covered for 15-20 minutes, until the vegetables are soft. Blend the contents of the pan with a stick blender until the soup is smooth, being careful not to splash the hot liquid and burn yourself. Season with pepper to taste and stir. Serve.
Recipe makes 4-5 bowls