In a large pot, heat the olive oil over medium heat. Add the diced onion, garlic, carrot, and celery. Sauté for about 5-7 minutes, or until the vegetables are softened.
Stir in the diced tomatoes (with their juice), cannellini beans, vegetable broth, dried basil, and dried oregano. Bring the mixture to a boil.
Reduce the heat and let it simmer for 20 minutes, allowing the flavors to meld together.
Season with salt and pepper to taste. Add the chopped spinach and lemon juice, cooking for an additional 5 minutes until the spinach is wilted.
Serve hot, garnished with fresh parsley.