I had one of these in a small family restaurant in Appleton, WI (go figure) and it was one of the best sandwiches I ever had.

The sandwiches are made with pulled pork shoulder that's been seasoned with a Puerto Rican rub instead of the traditional rub.  The pork is put in French bread (I didn't have access to the traditional Puerto Rican bread) and then topped with sliced ham, Swiss cheese, onion, pickle slices, mustard, and mayo.  The sandwich is then brushed with olive oil and put directly over the coals.  The key to the sandwich is weighting them down from the top after they're on the grill.  I used the lid from a cast iron dutch oven.  It presses the sandwich together and makes the juices soak into the bread.  Flip them over and do the same thing to the other side (that's the hard part of making this sandwich). 

The second time I made this, I used a round loaf of garlic French bread from a local bakery and made one large sandwich cut into wedges. 

This is the best sandwich in the world.  I swear.