Put the potatoes and vegetables in a suitably sized pan (one that holds them snugly in the bottom and about halfway up the inside). Cover with stock by about 2cm (go easy, you can always add more to adjust the consistency).
Bring to the boil, then reduce the heat and cook for about 10 minutes or until thoroughly heated through.
Liquidise the soup with a hand-held electric blender. Taste the soup and season. This is one soup that needs plenty of pepper.