Step 1

Heat the oil in a large lidded pan over a medium heat. Fry the onion for 4-5 mins, stirring from time to time, until softened. Add the sweet potatoes and toss to coat in the oil and onion. Reduce the heat, cover the pan and cook for 10-15 mins, giving the pan a good shake every few minutes.

Step 2

Pour in the stock and bring gently to the boil. Lower the heat and simmer for 15 mins. Remove from the heat and allow to cool. Blitz the soup with a stick blender until smooth. Season with salt and a grinding of black pepper, to taste, and reheat before serving.