1. Stir the mayonnaise, marmalade and oregano together in a small bowl.
2. Square off the ends of the bread and cut in half crosswise. Split each piece horizontally to hinge open. (If using Italian rolls, only split horizontally.)
3. Spread the flavored mayonnaise on the bottom of the breads. Top each with 3 slices of the ham, folding if necessary to fit on the bread, and then a layer of pickles and 3 slices of cheese. Finish each sandwich with 1/2 cup Pulled Pork. Spread the mustard on the top buns and close the sandwich.
4. Heat a medium cast-iron pan over medium heat. Melt the butter, add the sandwiches and press with a spatula to flatten. When the sandwiches are golden brown and crispy on the bottom, about 4 minutes, flip the sandwiches and press and cook until the cheese melts and the bread is golden brown, about 3 minutes more. Cut the sandwiches in half and serve.
Put the pork, chicken broth, vinegar, garlic, bay leaf and onion in a small Dutch oven and bring to a boil over medium-high heat. Reduce the heat to a very low simmer, cover and cook, turning the pork every 45 minutes, until the meat is fall-off-the-bone tender, 3 to 4 hours. Allow to sit for 15 minutes until the meat is cool enough to handle. Shred the meat with a fork. Makes about 8 cups.