I found this recipe on the parents.com website and decided to try it for my family. Although I couldn't find tostada shells, I substituted taco shells. With 2 kids, probably made for easier eating anyway. My family loved this and have requested I make this again! We also added Sour Cream and although I didn't have any guacamole, I think it would be a great addition to this recipe. Fix them up which ever way suits your taste. The meat is delicious!