Using mandolin slicer,thinly slice potatoes.
Heat a pot with water,salt and alum
Add the potato slices to water and boil them for 5 mins.
Remove them from the water, transfer to a pot to cold water for few minutes
Drain the excess water
Spread them evenly in a dehydrator or spread it out in the Sun
Dehydrate for 4-7 hours till crisp or 1-2 days in the sun.
Store in a dry air-tight jar.
Fry in hot oil whenever you wish to eat.