Cut the onions and beetroot into cubes. Sweat with a little butter and pour the vegetable stock on top. Let simmer for 5 minutes. Puree and season with cream, pepper, salt and finally with mustard. Now add the wieners cut into small cubes to the sauce, but do not boil any more.
Cook the spaghetti in salted water as usual.
Mix 2 fresh eggs with as much Parmesan or other cheese as you like in a bowl and mix with the freshly sliced bar leek.
Drain the spaghetti and mix with it immediately. Finally mix with the sauce.