Heat the olive oil in a large soup pot over medium heat. Add the onions, shallots and celery and cook for 3 minutes.
Add the beans and cook for an additional 2 minutes. Then add the plum tomatoes with juice and cook for 1 minute. Then add the chicken broth.
Drain the carrots, sweet peas, green beans and corn, and add to the broth.
Season the soup with thyme, salt and pepper and bring to a boil. Reduce the heat to low and simmer for 30 minutes.
Serve with grated parmesan, if desired.