In a frying pan fry the Italian sausages in the olive oil. While frying, chop up the carrots, celery and onion and add to the frying pan with the sausages and fry until the sausages have good color on each side and until the carrots/celery and onion have some color as well (do not need to be completely done before next step). Remove the sausages from the pan when color has developed.
In a separate large stock pot add the beans, broth, onion powder, garlic powder, dried celery, pepper flakes, mustard, Worcestershire sauce, sugar and vinegar. Tie the sage and rosemary in a bundle with kitchen string and add to the large stock pot.
Slice the sausages in disk shapes – about ½ inch thick – when cool enough to handle.
Add the sausages and the carrot mix to the sauce pot. Heat on Medium until bubbly – reduce heat to low. Add the parmesan and sour cream and heat through. Remove the herb bundle when ready to serve. Top with a croutons a dollop of sour cream and some parmesan cheese shavings.