To make your own ‘mince’.Cut the beef into 1-inch thick strips, toss to combine and chill on a baking sheet, uncovered, in the freezer for 30 minutes. Place the chilled beef into a food processor and pulse until the beef is broken down but not paste.
Form the beef into large patties, slightly larger than your slices of bread - you can use a burger press or your hands, or, as we used, a cookie cutter tin, to achieve perfect circles.
Heat a 12-inch cast-iron pan over high heat, drop a patty into the pan, season generously and start a timer. After two minutes, flip the burger. Put a couple slices of onion and two slices of cheese onto your burger. Add a lid and cook for a further two minutes until the cheese is melted and gooey.
Spread some american mustard on top of two slices of toast and place a patty on top of one. Sandwich the two slices together and cut in half. Serve with bread and butter pickles, ketchup and mustard
