In a large, heavy-bottomed pot or Dutch oven, heat the olive oil over medium heat. Add the diced onion, carrots, and celery. Cook gently, stirring occasionally, for 8 to 10 minutes until the vegetables are softened and the onions are translucent.

Add the minced garlic, dried thyme, and Italian seasoning. Stir constantly for about 1 minute until the garlic is fragrant. (Optional: add red pepper flakes here.)

Pour in the 4 cups of water and the 6 cups of vegetable broth. Scrape up any browned bits from the bottom of the pot. Add the can of diced tomatoes (including the juice) and the bay leaves.

Bring the mixture to a rolling boil. Reduce heat to a simmer, cover loosely, and add the diced potatoes and sweet potatoes. Simmer for about 15 minutes until the potatoes are almost tender.

Add the green beans, zucchini, corn, and peas. Stir well. Continue to simmer, uncovered, for another 10 to 15 minutes, or until all vegetables are tender but hold their shape.

Remove the bay leaves. Taste and season generously with salt and black pepper. Stir in the fresh spinach or chopped kale, letting it wilt for 2 to 3 minutes.

Ladle into bowls, sprinkle with fresh parsley, and serve immediately. (Optional: add a squeeze of fresh lemon juice for brightness.)