In small saucepan, stir together water and broth; heat to boiling. Add lentils; reduce heat. Simmer 35 minutes, covered, or until lentils are tender; drain. In medium saucepan, stir together spaghetti sauce, vinegar and drained lentils; heat to boiling. Reduce heat; cook 5 minutes. Heat oven to 375°. Meanwhile, cook pasta according to package directions. Stir together pasta and about 2-1/2 cups sauce; spread into 11- x 7-inch baking dish. Spoon remaining sauce over top, covering pasta completely; sprinkle with mozzarella cheese. Bake 10 minutes or until cheese melts.