Sandwich

This morning I discovered the latest in a series of lunch sack oddities on the part of our Katie. I suggested the child take a banana in her lunch, but she explained to me why this was simply not a good idea. Per Katie, bananas turn black the second they enter a backpack. (I wish someone had shared this tidbit with me when I was last baking banana bread and wishing for riper bananas.) Her solution is to instead take a whole bag of microwave popcorn. (My thoughts on how that does in her backpack over the hours between leaving the house and her snack time shall remain my own with the exception of, "Yuck.")
Prior to the great banana/popcorn issue, our favorite lunch sack point of contention with Miss Katie is her adamant refusal to take a sandwich or any other sort of entree approximation. She says she will take extra fruit. We have tried to explain to her that there are insufficient calories, protein, and calcium (I'm dancing around the kitchen waving yogurt or string cheese while singing "Calci-YUM!" without convincing her that these are good additions to her midday meal. She does believe that Mom is a big dork.) in the fruit to substitute for the lunchbox holy of holies--- a sandwich.
She says she would just throw a sandwich away, and she does not want to upset me by wasting food. Uh-huh. I wonder if she has given equal thought to how upset I will be when she is diagnosed with malnutrition. I have tried suggesting pretzels or crackers with cheese or peanut butter as an alternative to the dreaded sandwich, but little duckie doesn't like peanut butter or most cheeses. Anyone have any brilliant lunchtime substitutions to suggest?