When I was younger I used to live in a small town in Illinois and had a great Grandmother that live in a town called Table Grove. Whenever we would go visit her she would take us to a small diner there for lunch. It was a simple little place and didn't serve much of a variety of things. They had a toaster oven for making the Tombstone pizza's the served, and 28 years ago that was a pretty big deal. My favorite thing to eat at this diner was there fried pork tenderloin sandwich. It was a massive sandwich that had onion and pickles on it and I used to love to drench the thing in yellow mustard. Nothing has really changed in those 28 years I still love a good fried tenderloin sandwich and get a little annoyed when I order one and it doesn't meet the standard that little diner set. Not to long ago I was at a bar that had a fried tenderloin sandwich on the menu and got all excited to have one only to be disappointed when it got to the table. This particular bar had just fried a pork chop and put it on a bun. Everybody in the free world knows that a proper tenderloin sandwich is pounded flat and hangs outside the bun. I will not be going back to that spot.
A venison tenderloin is a lot smaller than a pigs but you can still manage to pound them flat and fry them for a great sandwich. What I like to do is take one venison tenderloin and cut it into 1 1/2 to 2 inch pieces then place each piece in a 1 gallon freezer bag and pound them flat one at a time. After they are about 1/2 inch thick, or thinner if you prefer, I take and dust each one with flour. for my egg wash I like to use one egg and a tablespoon of dijon mustard after the pounded pieces are coated in egg wash I coat them with bread crumbs. Any kind of bread crumb works, my brother likes to crush up croutons and use that. When all pieces are properly coated with bread crumbs you then fry them in oil on the stove top. Typically I will use canola oil and you only need about a 1/4 inch of oil in the pan. Then fry them for 3 or 4 minutes on each side until they are nice and golden brown. I like to season mine with Penzey's seasoned salt.
Pickles and onions make a nice topping for any fried tenderloin sandwich but today I just went with onions i just happenned to have a jar of pickled onions open so I used them. I still like to cover my tenderloin sandwiches in yellow mustard but you can use whatever you would like.