1. Remove the peas from the pods.
2. Wash the pods and cut off any hard or fibrous bits.
3. Put butter into a large pan.
4. Peel and finely chop the onion.
5. Fry the onion in the butter for a few minutes until soft and transparent.
6. Add the peas and the pods and cook for a few minutes.
7. Add the stock and mint leaves.
8. Bring to the boil and cook at a simmer until all the vegetables are tender.
9. Blend the cornflour with a little of the milk until it forms a smooth paste.
10. Stir the paste into the soup and add the rest of the milk.
11. Heat carefully, stirring until the soup boils.
12. Cook gently for a few more minutes.
13. Cool and liquidise the soup.
14. Reheat and serve with a little parsley.
