I've gone past Hash House A GoGo many times but had no idea it was that kind of restaurant. I see they serve the breaded tenderloin in various ways, including a sandwich. From the menu:
"Big O'crispy hand hammered pork tenderloin sandwich
"With onion, pickles & of course ketchup on a whole wheat bun served with your choice of side. You'll think you're back in Indiana!"
See www.hashhouseagogo.com for details. I will stop by Hash House A GoGo next time I'm in the vicinity -- thanks, BubblyOne.
I love breaded-pork-tenderloin sandwiches, too, and hope this thread finds something thoroughly Midwestern, preferably at a place that serves Jello for dessert and where you feel like helping the waitress clear away your dishes, Hon'.
Otherwise, you might think about trying Jägerhaus, where you can get decent German dishes, including a boneless breaded pork chop that could be turned into a (closed- or open-face w/gravy) sandwich quite easily. Board-favorite Pann's has excellent (when they're not overcooked) breaded pork chops, bone-in, that are convertible to sandwich duty with the aid of a sharp knife.
See attached photo for the real thing in Indianapolis.
Pann's Restaurant & Coffee Shop
6710 La Tijera Blvd, Los Angeles, CA 90045
2525 E Ball Rd, Anaheim, CA 92806