Prepare the Vegetables: Wash, peel, and chop the onions, garlic, carrots, celery, bell pepper, zucchini, and green beans into bite-sized pieces.
Sauté Onions and Garlic: In a large pot, heat the olive oil over medium heat. Add the chopped onions and minced garlic, sautéing until they become translucent.
Cook Vegetables: Add the diced carrots, celery, and chopped bell pepper to the pot. Cook for about 5 minutes, stirring occasionally.
Add Zucchini and Green Beans: Incorporate the sliced zucchini and green beans, cooking for an additional 3 minutes.
Include Tomatoes and Broth: Stir in the diced tomatoes (with their juice) and vegetable broth. Bring the mixture to a boil.
Season the Soup: Add dried basil, salt, and pepper. Adjust the seasoning according to your taste.
Simmer: Reduce the heat to low and let the soup simmer for about 20 minutes, or until the vegetables are tender.
Final Adjustments: Before serving, taste the soup and adjust the seasoning if necessary.