In a medium jug or bowl, combine burger sauce ingredients and set aside.
Prepare and preheat the barbecue for cooking using direct high heat (250°C-290°C).
Shape the mince into patties, make the patty a bit wider in diameter than Jatz as the mince will shrink.
Once the barbecue has preheated, place the mince patties topped with onion onto the grill. Press as thin as possible with the smash press. Grill over direct high heat for 2 minutes per side, or until cooked through.
When there is one minute left of cooking time, top with a small slice of burger cheese.
To make the mini smash burger place a meat patty and cheese, x 2, a dollop of burger sauce and top with another Jatz.
