Cook and shred chicken. Combine in crockpot with all ingredients except toritllas, & oil. Cook on low 6-8 hours or high 3-4 hours.
Preheat oven to 400 degrees. Cut tortillas into strips and place on baking sheet, brushing lightly with oil. Bake 5-10 minutes or until crisp. Immediately before serving, sprinkle tortilla strips over soup and serve with shredded cheddar cheese on top.