Cut the sausages diagonally into 2 cm pieces. Peel and finely chop the onion and garlic. Fry the sausage pieces in oil for approx. 5 minutes and remove. Sauté the onion and garlic in the frying fat until translucent. Add the lentils and sauté for 2 minutes. Pour in the soup, add the marjoram, cover and simmer the stew for approx. 30 minutes.
Peel the potatoes and cut into 2 cm cubes. Wash the leek and cut the white and green parts diagonally into fine rings. Halve the carrots lengthways and cut into slices. About 10 minutes before the end of the cooking time, add the potatoes, carrots and leek to the lentils and continue to cook, covered. 2 minutes before the end of the cooking time, heat the sausage pieces in the pan. Cut the chives into fine rolls. Season the stew with salt and pepper to taste and garnish with chives.