Dip container of frozen mix into hot water just to loosen. In 2 litre saucepan, heat frozen mix and remaining ingredients to boiling. Reduce heat; cover and simmer, stirring frequently, until mix is partially thawed, about 15 minutes. Uncover and simmer 15 minutes, stirring occasionally. While Meat Filling is simmering, Heat taco shells as directed on package. Spoon Meat Filling into taco shells. Top filling with cheese, lettuce and tomato. If desired, serve with taco sauce.