A 73-year-old woman in Indonesia has amazed onlookers with her incredible skill of slicing cassava with a knife on a cloth on her thigh.

Melwizar, who works at a Sanjai cracker factory in Bukittinggi City, West Sumatra Province, said she learned the technique from her parents when she was a child.

She said she used to help them slice cassava in this way since she was in elementary school or around 10-12 years old.

"This cassava is sliced thinly before being fried in hot oil to make the typical Sanjai chips," Mel said in a clip filmed today (July 11).

She added that sometimes she would injure her thigh or hand while slicing, but she would treat the wounds with a rub of rimbang leaf shoots, a traditional remedy.

Mel said she only started slicing cassava with a machine in 1981, when her father managed to make the first slicing machine.

Mel's cassava slicing skills have been widely praised for their speed and precision.