Sweat the shallot in oil, then add the potatoes and vegetable stock and leave to boil until the potatoes are soft.
Add the wild garlic and lamb lettuce and let it simmer for 1-2 minutes.
Leave the soup to cool slightly, then blend in a food processor (or using a stick blender) until smooth.
To make the croutons, place the bread on a baking tray, season with salt, pepper and olive oil and bake for 15 minutes at 180C
Serve the soup hot, topped with creme fraiche and croutons.