Clean, peel and slice the kohlrabis. Cook in boiling salted water with 1 teaspoon sugar for about 8 minutes. Peel and finely chop the onion. Drain and drain the kohlrabi, collecting 500 ml of the vegetable water.
Heat butter in a pan and fry kohlrabi for about 5 minutes while turning. Remove from the pan and put aside. Steam onions in the pan for about 2 minutes, dust with curry and flour, sauté for about 1 minute. Deglaze with vegetable water and cream. Add peas, bring to the boil and simmer for about 10 minutes.
In the meantime, heat oil in a pan and fry the sausages for 4-6 minutes, turning them until brown. Wash parsley, shake dry, remove leaves from the stalks and chop finely, except for a few for garnishing. Add kohlrabi to the peas in the pan, bring to the boil and remove from the heat. Season to taste with salt and pepper. Arrange kohlrabi vegetables and sausage on plates, garnish with parsley.