1Melt the butter in a saucepan and add the onion. Cook gently until the onion softens without colouring.
2Add pear and peas, vegetable stock and cover. Bring to the boil. Reduce heat and simmer for 10 minutes.
3Puree soup in a food processor or blender until smooth. Season to taste.
4Serve with croutons or crème fraiche if wished.