In a large bowl, combine ground beef, Montréal smoked meat, ham, panko, onions, BBQ seasoning, garlic salt and freshly ground black pepper. Using clean hands, mix the ingredients until well blended.
Form 4 patties with the mixture and place them on a plate.
Cover tightly with plastic wrap and transfer them to the fridge for 1 hour.
Mix all the mustard sauce ingredients in a small bowl; set aside.
Sixty minutes later, take the patties out of the fridge, remove the cling film and let them sit on the counter for about 20 minutes.
Preheat the barbecue to 500ºF
Place the patties on the grates, close the lid and grill them for about 6 to 7 minutes on each side.
Three minutes before they’re done, place the hamburger buns on the top rack to toast, about 2 minutes. Remove the buns and set them aside.
Place a couple slices of processed cheese, close the lid and cook until melted, about 1 minute.
To assemble the burgers, place lettuce, meat patty, a slice of tomato, hot banana peppers and then spread a generous amount of our mustard sauce on the bun.