To make the sweet potato fries, turn on the grill to a medium heat. Place the sweet potato chips in a baking tray and add the olive oil. Toss to coat the fries in the oil, and then add the flour, a good pinch of salt and the mixed herbs, if using.
Toss again to coat the fries, then place them under the grill for 30-35 minutes, until golden and crisp, turning mi