Start by washing the potatoes, scrubbing any dirt off of the skin (leaving the skin on)!
Pat dry and slice into thin wedges. Add to a large bowl and cover with cold water. Leave to soak for 30 minutes.
Remove the wedges from the water and pat dry with a clean tea towel to remove the moisture.
To a large mixing bowl, add the rapeseed oil, smoked paprika, cayenne pepper, onion salt and cornflour. Add the sweet potato wedges and stir until everything is evenly coated.
To a lightly greased baking tray (use oil spray if you have), distribute the wedges across the tray, ensuring no overlapping/touching. I used two trays to prevent this.
Pop in the oven for 20 minutes then rotate the wedges and cook for another 20. Depending on how thinly you sliced your wedges, this time will vary so keep an eye out!
Remove from the oven and season with flakey salt. Enjoy!