Heat olive oil in a large pot over medium heat.
Add the chopped onion and cook until translucent, about 5 minutes.
Add the minced garlic and cook for another minute.
Stir in the carrots, celery, zucchini, and green beans. Cook for about 5 minutes, stirring occasionally.
Add the diced tomatoes, vegetable broth, dried basil, dried oregano, salt, and black pepper. Bring to a boil.
Reduce the heat and let it simmer for about 20 minutes, or until the vegetables are tender.
If using, stir in the chopped kale and cook for another 5 minutes.
Adjust seasoning to taste and serve hot.