Giroud was onside.
It was a beauty - Mkhitaryan's was better, though.
It's not even comparable. Not only is Giroud's goal a good goal contrary to Mkhi's, it's also set up by one of the best counter attacks you'll see all season. It's literally a perfect goal right from when Perez wins the ball, up to Giroud's finish (which was his second backheel in the move).The only thing Giroud's has over Mkhi's is that his was actually onside!