Preheat oven to 375⁰F/190⁰C. Grease and line a baking sheet. Set aside.
In a clean bowl, mix ground beef and ground pork.
Add onion, yellow mustard, bbq marinade sauce, liquid smoke flavor, salt, pepper, egg, and flour. Mix well, until well blended. Marinate the burger mixture over night.
Divide the burger mixture into 5 parts and form into a burger patty.
Heat oil on a medium-sized pan, over medium heat.
Sear burger patties and let it cool.
In a clean surface, lay one sheet of puff pastry , at the middle of the pastry, lay one slice of cheese, top with cooked burger patty, then top again with a slice of cheese. Cover with another piece of puff pastry .
Fold the ends together to completely cover the burger and then press the seams together. You should have a closed pocket or dome like puff pastry burger. Continue doing the procedure until all burger patties have been covered.
Bake the cheeseburger puffs for 10 to 15 minutes or until the puff pastry turns brown, flip the pastry then bake for another 10-15 minutes to cook on the other side.
Then take the cheeseburger puff out of the oven and brush the top of it with egg wash and sprinkle it with sesame seeds and put back inside the oven and finish baking it for another 5 minutes.
Serve with tomato, lettuce, catsup, and mustard on the sides.