In a mixing bowl, combine the mince, Spanish onion, garlic, salt and pepper. Massage well.
Put a frying pan with a splash of oil on to heat. Fry the onion rings until softened. Add the bacon and fry until crispy. Set aside the bacon and onions.
Mould the mince mix into burger patties, then fry for approximately 2-3 minutes on each side.
Place down cos leaves, then place on the burger, bacon, onion, cheese, chilli jam, then a blob of mayonnaise. Enjoy.