In a large pot, heat the olive oil over medium heat. Add the chopped onion and minced garlic, cook until translucent.

Toss in the sliced carrots and chopped celery. Sauté for about 5-7 minutes.

Pour in the vegetable broth, add the bay leaf and dried thyme. Bring to a boil, then reduce to a simmer for about 15 minutes.

Add the zucchini, bell pepper, and green beans. Cook for another 10 minutes until tender.

Remove the bay leaf and season with salt and pepper to taste. Let simmer for another 5 minutes.

Ladle into bowls and garnish with parsley and croutons if desired.