Sauté Aromatics:
Heat olive oil in a large pot over medium heat. Add the diced onion and cook until softened, about 3–4 minutes. Stir in the garlic and cook for another 30 seconds.
Cook the Vegetables:
Add the carrots, celery, zucchini, bell pepper, and green beans to the pot. Cook for 5–6 minutes, stirring occasionally, until the vegetables begin to soften.
Add Tomatoes and Broth:
Stir in the diced tomatoes (with their juice), vegetable broth, thyme, oregano, bay leaf, and a pinch of salt and pepper. Bring the mixture to a boil.
Simmer the Soup:
Reduce the heat to low and let the soup simmer uncovered for 20–25 minutes, or until the vegetables are tender.
Finish with Greens (Optional):
If using kale or spinach, stir them into the pot during the last 5 minutes of cooking. Add frozen peas at this stage as well if desired.
Taste and Adjust:
Remove the bay leaf, taste the soup, and adjust the seasoning with additional salt and pepper as needed.
Serve:
Ladle the soup into bowls and garnish with fresh parsley. Serve hot with crusty bread or crackers.