Once knew a lady from Iowa who introduced me to boiled ground beef. She said it was the feature at a local diner there. You simply chop up the already ground beef and dump it into a pan of boiling water until cooked, then spread on a sandwich with whatever topping you like.
My mother used to take ground beef with minced onion, spread it on a piece of white bread. She would then place it under the broiler until it sizzled.
Have never heard of anyone else making the above two dishes anywhere, ever.
And about subs...here in northern PA they are called subs. They never heard the word "hoagie" up here at all. And if I said "grinder" they'd probably think I was referring to Minnie Pearl's Grinder's Switch!

"Adversity is the whetstone of creativity"