Bring A Large Pot Of Lightly Salted Water To A Boil. Add Pasta And Cook For 8 To 10 Minutes Or Until Al Dente; Drain. Drain Diced Tomatoes, Reserving 2 Tablespoons Of The Liquid. Microwave Onion, Garlic And Mushrooms, And Reserved Liquid In A Large, Loosely Covered Dish For 2 To 3 Minutes Until Onions Are Clear. Add Tomato Sauce, Italian Seasoning And Tomatoes To Onion Mixture And Microwave 5 To 6 Minutes More Or Until Heated Through. Pour Over Cooked Pasta.