Clean and wash the soup greens. Cut carrots into thin slices and leek into rings. Dice celery. Rinse celery green briefly and chop. Heat oil in a pot. Fry the soup greens over medium heat for about 2 minutes.
Add 3/8 litres of water and dissolve the stock cube in it while stirring. Cook the vegetables for about 10 minutes in the stock. Put the lentils on a sieve and rinse briefly with cold water. Add to vegetables and simmer for another 5 minutes.
First cut the sausage into thick slices, then dice it and heat it up in the stew. Season with pepper. A crispy rye mixed bread tastes good with it.