1. In a large saucepan, heat oil. Sauté onions, carrots, and zucchini.
2. Add meat and cook for five minutes, until browned and broken up.
3. Add tomato sauce, then fill the empty can with water and add that water to the saucepan.
4. Add marinara sauce and salt and pepper to taste.
5. Bring to a boil and add spaghetti. Reduce heat and cook about 30 minutes, until pasta is cooked and water has evaporated.