Onion peel and in rough cubes cut. Peel and wash the potatoes and cut into smaller cubes. Wash and clean carrots and cut into fine slices. Leek onions clean, wash and cut into fine rings.
Heat the oil in a pot. Add diced onion and half of the vegetables to the pot and steam for about 5 minutes. Fill up with broth and simmer for about 10 minutes. Puree the soup with a chopping stick.
Add the remaining potatoes and carrots and cook for about 8 minutes until firm to the bite. Add spring onions and continue cooking for about 2 minutes. Season soup with salt, pepper, sugar and a dash of vinegar. Put 4 sausages lengthwise on each skewer and add to the soup.