Gather all the ingredients. Mix the turmeric, salt, and water in a little bowl and set aside.
Cut off the ends of the plantain.
Make a cut lengthwise down the plantain, just enough to go through the peel. Then gently remove the peel. If you're going to peel more than one plantain then it might be a good idea to oil your hands lightly to prevent the sap from the plantain skin from sticking to your hand.
Don't throw away the peel, you can make thoran with it.
Unrefined coconut oil is absolutely essential if you are going for the authentic taste of Kerala chips. Heat 1 - 2 inches of oil in a pan to around 375°F (190°C). Drop one slice to see if the temperature is just right. If it bubbles and floats to the top you are ready to go.
Taking great care thinly slice the plantain with a mandoline (on the thinnest setting) directly into the hot oil. Alternatively, you can slice them using a knife or a mandoline on to a cutting board beforehand and add them to the oil when it's hot. Give it a gentle stir to prevent clumping.
Add the turmeric and salt water and stir gently to mix.
After a minute or two add the curry leaves and the green chilies. Cook for another minute.
Remove and drain on a kitchen towel.
Enjoy! In the unlikely event you have leftovers, they can be stored in an airtight container for a couple of weeks.