Peel the carrots and cut into slices. Wash zucchini, quarter lengthways and cut into pieces. Dice the kohlrabi and paprika. Peel and dice the potatoes.
Heat the oil in a large saucepan and sauté the vegetables and potatoes in it. Season with salt, sugar and pepper. Pour in the stock, bring to the boil and simmer for 20 minutes.
Chop the parsley and slice the sausages. Add both to the soup and serve.