1 (10 ounce) package Tostada packages
1/4 cup margarine
1 (4 ounce) can sliced mushrooms, drained
1 large onion, diced
10 black olives, halved
1 (8 ounce) can tomato paste
1 (4 ounce) jar salsa
1 (16 ounce) can whole kernel corn, drained
2 pounds shredded Cheddar cheese, diced
Rub bottom and sides of a large resealable plastic bag with margarine. Reserve about 1/4 cup of the margarine and grease the sides of the plastic bag. Heat margarine in a large skillet over medium heat. Add mushrooms, onion, and olives. Saute for about 20 minutes over medium heat. Add tomato paste, salsa, corn and cheese; stir with spoon. Pour blended mixture into plastic bag with margarine. Stretch seam open.
Return plastic bag to pan and place lid on top of pan. Cover container and steam about 15 minutes.