Okay, this might be common knowledge for everyone. If it is I'll be incredibly embarrassed. But I found a way to make crunchy wedges with no oil whatsoever tonight and I'm really stoked!
What did I coat them in? Corn flour. I put a few tablespoons of cornflour and some spices in a bag, cut up the potatoes into wedges, threw them in the bag and shook it for a while to coat them. Then I just laid them out on aluminium foil skin side down on baking trays and baked them in the oven.
They're delish!