Wash the sweet potatoes with fresh water and using a sharp knife cut them lenghtwise. Then, cut each half into wedge shapes.
Using a mixing bowl, add the cornflour and water and stir well until all the cornflour has been diluted.
Add the wedges into the mixture and coat well making sure all the sweet potato wedges are evenly coated.
Using a small pan (it will reduce the amount of oil needed), add vegetable oil, enough to deep fry the wedges, and heat the oil to a high temperature.
When the oil is hot enough, start adding the wedges. You may need to fry them in batches to avoid overcrowding the pan.
When golden, take the wedges out of the oil and place them on kitchen paper. Sprinkle with salt, leave them for a couple of minutes to release any excess oil, and transfer them into the serving bowl.
Add the lime zest on the top and enjoy!