I'm not a fan of sweet potato fries but my mum loves them.
A quick and simple 'recipie' is to cut a large potato into reasonably similar sized chips, wedges or even square types and boil them for about 8 or so minutes till it starts to get soft (but not so soft that they fall apart) and preheat the oven on GM7 whilst they boil.
Drain them and line a baking tray with greaseproof paper, spray liberally with frylight (shake them around the paper for a bit so the bottoms are coated too) and then sprinkle with paprika and mixed herbs over the top. Bake for about 40 mins, shaking them around a bit again around halfway through so they're cooked through both sides.
Tastes the same as chips to me and much healthier than frying or lathering in oil.