Put a large pan on a medium heat and fry the bacon lardons until golden. Take off the heat and remove half of the lardons from the pan. Put them in a bowl to use later.

Peel the potatoes and chop into inch sized pieces.

Put the pan (with the remaining half of the lardons in) back on a medium heat and add the onion. Fry for five minutes, stirring often. If the pan is dry, add a dash of olive oil.

Add the potatoes and vegetable stock. Bring to a boil then simmer for 30 minutes.

When the potatoes are cooked through, use a blender to whizz into a smooth soup. Taste, then season with salt and pepper. If the soup is very thick, you can add a little hot water to loosen it to your preferred consistency.

Put the spinach in a colander and pour over some boiling water to wilt it.