Preheat your oven to 300.  Lined a baking sheet with parchment and place the cooling rack on top. Wash and scrub the beets thoroughly and slice into thin slices.  Put into a bowl and salt and let stand. Letting the beets stand with salt will take out any moisture that will prevent too much shrivelling.  Place into a different bowl and season with apple cider vinegar, diced rosemary and olive oil. Line the sheet and bake low and slow about 30 minutes on one side, and then flip and cook another 30 minutes until the beets are nice and crispy.   Let the chips cool, season more if you like and enjoy.