2 cans water packed tuna (drained & flaked)
1 lg. onion, chopped
8 corn tortillas (cut in bite-sized pieces)
1 can cream of mushroom or cream of chicken soup
1 can Rotel tomatoes

Mix all ingredients. Spray 13 x 9 x 2 inch pan with Pam. Fill ingredients. Cook in 400 degree oven for 30 minutes. If desired add grated cheese or grated light cheese on top. Cook 5 more minutes. Serves 8.