Prepare the Vegetables: Wash and chop all the vegetables into bite-sized pieces. Dice the carrots, celery, zucchini, broccoli, cauliflower, bell peppers (if using), and chop the leafy greens. Mince the garlic and finely chop the onion.
Sauté the Aromatics: Heat 2 tablespoons of olive oil in a large pot over medium heat. Add the chopped onion and minced garlic, and sauté until soft and fragrant, about 2–3 minutes.
Add the Vegetables and Broth: Add the diced carrots, celery, zucchini, green beans, broccoli, cauliflower, optional bell peppers, peas, corn, and diced tomatoes (if using) to the pot. Pour in 4 cups of vegetable broth and stir in 1 teaspoon of dried thyme and 1 teaspoon of dried oregano. Bring the mixture to a gentle boil.
Simmer and Cook: Reduce the heat to low and let the soup simmer for 20–25 minutes, or until the vegetables are tender but still slightly firm. Stir occasionally and taste to adjust salt and black pepper.
Add Leafy Greens: Stir in 2 cups of chopped spinach or kale during the last 3–5 minutes of cooking.
Serve and Garnish: Ladle the soup into bowls and garnish with fresh parsley or cilantro. Serve hot with sides like vegetable fried rice, garlic rice, or herb and cheese bread.