In a large pot, heat the olive oil over medium heat. Add the onion, carrots, and celery. Sauté for about 5 minutes until the vegetables begin to soften.
Stir in the garlic and bell pepper, cooking for an additional 2 minutes until fragrant.
Add the chopped cabbage, diced tomatoes (with juice), vegetable broth, thyme, basil, salt, and pepper. Bring the mixture to a boil.
Once boiling, reduce the heat to low and let it simmer for about 20 minutes.
Add the green beans and zucchini, and continue to simmer for another 10-15 minutes until all vegetables are tender.
Stir in the lemon juice before serving. Adjust seasoning if necessary.