Put the oil in a saucepan and sauté the onion, garlic, ginger and chilli. Add the sweet potatoes and carrots and sauté for another 2-3 minutes. Now deglaze with vegetable stock and fill up - about enough to cover everything with a finger`s width. Let simmer for about 20-25 minutes. When everything is done (do a knife test), then mash or puree and season with salt and pepper. Then serve and garnish with spring onion rings or chopped parsley.
Tip: Nothing goes wrong with this soup. You can let your imagination run wild here. For example, add more sweet potatoes or normal potatoes.