Tuna Sopa Soca - cooking recipe

Ingredients

1 c. chopped onion
1 (10 1/2 oz.) can Ro-Tel tomatoes with green chilies
1 (10 3/4 oz.) can cream of mushroom soup
2 (6 1/2 oz.) cans tuna, drained
8 (6-inch) corn tortillas, torn up to bite-size
1 1/2 c. shredded sharp Cheddar cheese, divided

Preparation

Note:
I use flour tortillas; we think it is better.