The sound of fruit in a stew seems yummy to me. When you mentioned dulce de membrillo, being used in a sandwich with cheese, you reminded me of a grill cheese I used to make and forgot about.
Would slice up apples, use cheddar cheese and put in a barbecue sauce like hickory bbq sauce. Oh forgot to mention, cook up some bacon, and throw it in there as well. Can't forget the bacon! I know what Im having for lunch now! :D