In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until translucent.
Stir in the minced garlic and cook for an additional minute, until fragrant.
Add the sliced carrots and diced celery to the pot. Cook for 5-7 minutes, stirring occasionally, until the vegetables begin to soften.
Add the chopped cabbage and zucchini to the pot, stirring to combine.
Pour in the diced tomatoes with their juice and the vegetable broth. Add the dried thyme, oregano, salt, and pepper. Bring the mixture to a boil.
Reduce the heat to low and let the soup simmer for about 30 minutes, or until all the vegetables are tender.
Stir in the lemon juice just before serving. Adjust seasoning if necessary.
Serve hot, garnished with fresh parsley.