In a small bowl, whisk together the Cuba spice, salt, oil and orange juice. Cut 1-inch long slits across the fatty side of the pork roast. Place pork in a large zip-top bag and pour marinade over the roast. Close bag, making sure to squeeze out all of the air, and massage marinade into pork. Refrigerate for at least 1 hour, up to overnight (the longer, the better)! \nPreheat oven to 425 degrees.\nPlace pork on a roasting rack inside a roasting pan. Cook for 15 minutes, then reduce the heat to 375 degrees. Continue roasting until the pork reaches an internal temperature of 145 degrees, about 1 hour - 1 hour 15 minutes more. Transfer pork to a cutting board and cover with foil. Let rest for at least 20 minutes before thinly slicing.\nFor assembly, slice bread lengthwise and cover both halves with mustard. Layer ham on the bottom buns, followed by a hearty layer of thinly sliced pork. Top with pickle slices and Swiss cheese. Place the top bun on top and sandwich together. \nMelt butter in a large skillet over medium heat. Once the butter is sizzling, place sandwiches in pan, pressing down firmly. Once one side is golden brown and the cheese is beginning to melt, flip and toast the other side.\nRemove from the pan once heated through and the cheese is melted. Cut sandwiches in half and enjoy!