Heat oil in a large saucepan, add onion, garlic and celery and cook over medium heat 5-10 minutes until softened.
Add potatoes and stock and bring to the boil. Simmer 10 minutes or until the potatoes are soft. Add peas and simmer 5 more minutes. Add the mint and cream.
Place mixture in a blender and puree until almost smooth. Season to taste and reheat.