1. Pulse bread in a food processor until coarse crumbs measure 1/2 cup. Combine crumbs and milk in a bowl.

2. Heat olive oil in a large skillet over medium-high heat. Add onion and carrot; sauté 8 minutes. Add garlic and tomato paste; sauté for 1 minute, stirring constantly. Add vinegar; cook for 30 seconds. Add oregano, salt, peppers, and beef; cook 7 minutes, stirring to crumble. Stir in breadcrumb mixture and tomatoes; bring to a boil. Reduce heat, and simmer for 6 minutes, stirring occasionally. Serve over spaghetti; top with cheese.