In a large pot, heat the oil over medium heat. Add the mushrooms, garlic, and bell pepper and cook for about 5 minutes, until mushrooms are almost tender, stirring often. Season to taste with salt.
Add the diced tomatoes, tomato sauce, and water or stock. Bring to a boil. Reduce heat to medium and simmer for about 15 minutes, until vegetables are tender, stirring occasionally.
Stir in beans (rinsed and drained if using canned beans) and kale. Cook for about 2 minutes or until kale is wilted. Ladle into bowls and top with Parmesan cheese. Enjoy!