In a large pan, bring the stock to the boil.
Add the mangetout, potatoes, onion and mint to the liquid.
Simmer for 15-20 minutes until the vegetables are tender.
Taste and adjust seasoning as necessary.
Remove from heat and leave to cool.
Whizz the soup through with a hand blender until smooth.
Serve immediately for a cold soup, otherwise heat through and serve.
