Set oven to 225C/425F with the fan on full blast.Wash and peel the sweet potato. Cut into thick wedges.
Season the fries with salt and toss. Add the cornstarch and toss well.
Get two trays and line them with parchment paper. Add the oil and spread across the two trays. Line up the dusted sweet potato fries across the two trays.
Roast the sweet potatoes in the oven for 10 minutes. Then turn each wedge over on the tray and put back in the oven until nicely coloured and crispy. Aprox. 5-10 minutes more.
Season the fries with a bit more salt and drain on paper towel. Serve right away.
Notes
Be careful not to burn yourself when removing the trays from the oven because of the hot oil. Serve right away as the crispiness does not last long.