So last night, Mama Awesome and myself went to Solstice services. The food they served afterwards was totally fantastic, and the best part was the "caramelized onion and feta" sandwiches. It was just caramelized onion on flatbread that had been spread with feta (I did not know that you could spread feta, and it was creamier than feta, so my guess is that it was something more like laughing cow cheese.)
I have a hard time finding good vegetarian sandwiches, so I was so pleased to try something that would be easy to make and fairly portable which did not involve sprouts. I think one could easily make caramelized onions in the slow cooker and then refrigerate them for an indefinite period of time to have a constant supply for sandwich making.