Peel the potatoes, carrots and kohlrabi and cut into cubes of roughly the same size. Clean the leek and cut into thin rings. Finely dice the onions.
Fry the onion and bacon cubes in a tall saucepan with the oil until the onion is translucent. Add the potato, kohlrabi and carrot cubes and fry everything a little more. Now add the leek, mix in and deglaze everything with the meat stock. Season the stew with vegetable stock powder and pepper, bring to the boil briefly and then simmer over medium heat with the lid closed for approx. 30 - 45 minutes, stirring occasionally.
In the meantime, cut the sausages into slices and add them at the end of the cooking time. Let the stew steep for another 10 minutes and serve.