1. Coat large skillet with nonstick cooking spray and heat over high.
2. Add turkey and cook, stirring, until brown through (5 minutes). Drain off and discard fat.
3. Stir in tomatoes with their liquid, green pepper, onion, garlic, oregano, and pepper. Bring to boil.
4. Reduce heat and simmer, covered, until vegetables are soft and well cooked down (25-30 minutes).
5. While sauce is cooking, cook spaghetti according to directions. Top spaghetti with sauce to serve.