Migas are a delicacy as old as tortillas. The word is Spanish for “crumbs"—specifically the crumbs of tortillas of a certain age. North of the border, the tortilla fragments are usually served with salsa, beans, and sour cream.
The basic concept of cooking old chip shards has been independently invented countless times by folks who are weary of dipping increasingly smaller chips into their bowl of salsa, and wish for some way to use those tasty, unwieldy crumbs at the bottom of the bag. That weary tortilla eater was me when I invented migas.