Peel and dice the potatoes. Finely chop the garlic, cut the onion and leek into rings.
Heat the oil in a saucepan and sauté the onion rings and chopped garlic. Add the leek rings and potato cubes and fry with them.
Clean and wash the Brussels sprouts, cut the stalk crosswise and add the Brussels sprouts to the pot. Pour in the broth, bring to the boil and cover the soup for about 20 minutes. Season with salt, pepper and nutmeg.
Cut the chives into fine rolls. Fill the Brussels sprouts soup into plates, sprinkle with chives and serve with 1 tablespoon of sour cream.