Remove the silvery thin skin from the Pork Tenderloin(s). Ususally they come 2 to a package. Slice medallions about 2-2 1/2" thick. Place 1 medallion, flat, not on its side, in a Ziplock and pound with a meat mallet to about 1" thickness. Use the flat side of the mallet (if you don't have a mallet, the edge of a saucer or the bottom of a coffee cup will work just fine) you don't want to tear up the meat.
I generally get 12-14 medallions out of both pieces of tenderloin (which would be 12-14 sandwiches)
Whisk eggs and milk together (You may need more egg wash, depending on how many tenderloins you are making) Place sleeves of crackers in a Ziplock and crush, I use a rolling pin.
Pour enough oil in a frying pan to coat the bottom, as if you were frying chicken. Pre-heat the oil so it's ready to sizzle when you add your tenderloin. A good way to tell is to put the handle of a wooden spoon in the oil and if it bubbles up it's ready, you want to hear the meat sizzle when it goes in the pan.
If you are cooking all 12 pieces you may need to change your oil, or remove some of the drippings and add more oil. The excess breading, when doing several, will burn so you need to scoop it out and add oil as needed.
Dip the pork tenderloin in the egg, then press into the cracker crumbs so it's well coated. Fry about 7 minutes on each side, until it's golden brown, and then flip and fry the other side.
When tenderloins are done, remove and drain on paper towel. From there serve on nice large buns with mayo, catsup, sliced onion, lettuce and tomato.
You can actually make these a day before you are going to serve them. Put them on a cookie sheet, cover and store in the fridge. Reheat in the oven uncovered, at 350 for about 20 minutes to serve just before your gathering.