Peel the shallots and cut into small pieces. Wash marjoram, pat dry, set aside for garnish, chop the rest. Peel and wash the carrot, cut into pieces. Peel, wash and cut the potatoes into pieces.
Put the carrot, marjoram, shallots and potatoes in a saucepan with 1 liter of water. Bring to the boil, stir in the stock and simmer covered for approx. 30 minutes over a mild heat.
Leave the bacon crispy in a hot pan, drain on kitchen paper.
Remove some of the potato and carrot vegetables from the soup. Puree the soup finely, melt the butter in it. Season to taste with salt and pepper. Add the potatoes and carrots to the soup again.
Serve the soup with bacon and garnish with marjoram.