Warm the pot. Heat olive oil in a large pot over medium heat. Add onion, carrots, and celery. Cook 5–7 minutes, stirring, until the vegetables soften and the onions look translucent.
Build the base. Stir in garlic and cook 30 seconds until fragrant.
Add dried oregano, thyme, and red pepper flakes if using. Toast the spices for another 30 seconds to wake them up.
Add hearty veggies. Add potatoes, zucchini, and green beans. Stir to coat in the aromatics.
Pour and simmer. Add the tomatoes and vegetable broth.
Drop in the bay leaf and Parmesan rind if using. Bring to a gentle boil, then reduce to a steady simmer. Cook 20–25 minutes, or until the potatoes are tender.
Stir in beans and greens. Add the cannellini or kidney beans and the spinach or kale.
Simmer 3–5 minutes, just until the greens wilt and the beans are warmed through.
Finish and season. Remove the bay leaf (and Parmesan rind). Add a squeeze of lemon juice and taste. Season with salt and black pepper until the flavors pop.
Serve. Ladle into bowls and top with chopped parsley.
Add grated Parmesan if you like (skip for vegan). Serve with crusty bread.