To make the crisps, heat the oil in a large pan or in a deep fat fryer. (CAUTION: Hot oil can be very dangerous. Do not leave unattended.)
Slice the sweet potato on a mandolin. They should be round, thin discs.
Once the oil is heated, fry the sweet potatoes.
Drain on kitchen paper.
Season with salt and freshly ground black pepper.
Serve in a large bowl.