Preheat oven to 180°C.  

Mix together the oil, cider and a pinch of salt.  

Peel, trim and thinly slice, with a mandolin, the beetroot.  

Throw beetroot into bowl and coat each piece in the vinegar mixture.

Lay in a single layer on a tray lined with baking paper.  Bake for 20 mins, then turn oven down to 100°C for a further 10 mins or until crispy.  For really flat chips, lay another sheet of baking paper and a baking tray on top to weigh them down while cooking.