Cut the spring onions into pieces. Cut the meat sausage into thin slices. Heat oil in a large pan. Fry the sausage in it while turning, remove. Fry the spring onions in the frying fat. Dust the flour over it and sauté briefly. Deglaze with milk and 1/4 l water, bring to the boil. Stir in the stock, mustard and sour cream, season to taste. Add the sausage, simmer everything for 1-2 minutes. Wash, chop and sprinkle the parsley.
Farmhouse bread and radishes or mashed potatoes go well with this.