#12 - Mitraillette
Country of origin: Belgium 
Twice fried fries (frites) and fried meat with sauce on a demi-baguette.
I'm half Belgian and have often visited family there over the years.  The Mitraillette is not very commonly known outside of Belgium, but I always try and get one when visiting.  The name means "machine gun"
The variety of sauces you find at Belgian Friteries is enormous and you can really make this sandwich your own. I keep it simple with mayo or a good andalouse.  If you've ever put fries in your sandwich, this may be where that originated from.  If you're not into that, you should probably visit the source for the best fries in the world and try it in a sandwich before saying that.  The most common meat used is a type of Belgian meatball that is sliced.
Funny note, these are also served in Northern France, where they are called "Americain" or "The American". 
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