In a 5 quart heavy bottomed pot, heat the olive oil for 1 minute over medium-high heat. Add onions, carrots and celery. Add a pinch of salt to the vegetables and cook until they begin to soften; about 5 minutes.
Add garlic, oregano, bay leaf and a pinch of black pepper. Cook for 1 minute.
Stir in remaining ingredients. Bring soup to a boil, then reduce heat to low. Cover and simmer for at least 20 minutes, or up to an hour. Stir in freshly chopped parsley just before serving.
About 10 minutes before serving, boil a pot of water for the pasta and cook to al dente. Drain and set aside.
To serve, spoon desired amount of pasta in each bowl and ladle soup over the pasta. Garnish with chopped parsley and grated Parmesan cheese, if desired.