1. In a soup pot, heat the oil over high heat. Add the steak, onion, garlic, and pepper. Sauté 6 to 8 minutes, or until steak and onions are browned, stirring frequently.
2. Add yellow squash, reduce heat to medium, and cook 3 to 4 minutes, or until squash is tender. Add beans, tomatoes, and basil; mix well. Cook 3 to 4 more minutes, or until heated through.
3. Just before serving, stir in spinach and cook 2 to 3 minutes, or until spinach wilts.
Optional: Grating fresh Parmesan cheese over this right before serving.