Cut the sausage into slices. Peel onions and cut into rings. Fry both in hot oil while turning for about 3 minutes, remove. Fry the vegetables in the frying fat for 3 minutes over high heat.
Add stock, bring to the boil briefly. Add sausage and onions and cook for another 4 minutes. Season with salt and pepper. Wash the parsley and, except for 1 stalk for garnishing, chop and sprinkle on top.