How to bake perfect crispy sweet potato fries

1. Cut the sweet potatoes into 5mm (¼in) slices. Soak in cold water for 45-60 minutes. This draws out the excess starch from the sweet potatoes, helping them to cook all the way through.
2. Preheat the oven to 200°C/Gas Mark 6. Line 1-2 baking trays with greaseproof paper. Warm the tray in the oven.
3. Coat the slices in oil, but not too much or they will be very soft when they come out of the oven. Mix the slices, cornflour and oil in a large bowl, using your hands to distribute the oil and cornflour evenly. If you’re adding seasoning, do it now as the oil will help the spices stick to the sweet potato. If you’re adding salt, do so after the chips have cooked as adding salt before cooking draws moisture from the fries and creates more steam in the oven.
4. Place the sweet potato slices on the baking trays, making sure to leave plenty of room between each chip to allow as much moisture as possible to evaporate to ensure they stay nice and crispy, and cook in the oven for 30-40 minutes (depending on your oven). Turn the fries over halfway through cooking. It is best to cook sweet potato fries in the higher shelves of your oven, slightly further away from the heat source so that the sugars do not caramelise too quickly and end up burning the chips. If you are cooking your fries on separate trays, make sure you swap the trays mid-way through cooking so all the chips bake evenly.
5. Once your fries have cooked, turn the oven off and leave them in the oven for an extra 10 minutes so that they have extra time to crisp up without burning.

TIP

The most important thing to remember is not to cook too many fries at once, and to spread them out evenly on a baking tray –  leaving enough room so that they don’t touch.