I had the Xinjiang Polo (Lamb over Fried Rice) dish above for lunch again, today and confirm there were no potatoes or carrots harmed in its making. There was however, carrot in the accompanying side of stir fried beg.
I'm sorry, but I still have no better explanation for what we both saw as possible potato in the photo I posted.
I look forward to seeing your version, if you get round to making it.