Peel and dice the potatoes.
Thinly slice the leek and chop the carrot and garlic.
Heat the oil in a large pot, sauté the leek and garlic for 5 minutes, then add the potatoes and carrot.
Add the stock and bay leaf and bring to the boil. Gently simmer for 15 minutes or so until the potatoes have softened. Add most of the dill. Using a stick blender, process the soup until you get a smooth, silky soup.
Add the drained beans and bring back to the boil.
When warmed through, add the cider vinegar and serve with chopped dill and crème fraîche, if liked.