Cut off both ends of the yellow plantain and discard them.
Slice the peel lengthways (not too deep) then remove and discard the peel.
Transfer the plantain in a bowl of water with a teaspoon of pink salt and allow to soak for 10-15 minutes (this helps to remove the starch and yield more crispiness).
Drain and rinse the plantain using a colander.
Blot the plantain dry with kitchen paper.
Use a mandolin slicer or paring knife to slice the plantain into thin disc (the thinner they are, the crisper they will be).
Preheat the air fryer.
Transfer the plantain chips and pink salt into a large bowl.
Use your hands to toss and coat the plantain chips in the oil.
Line your fryer basket with a paper liner (this is optional).
Place the chips in the air fryer basket and arrange in a single layer with some overlapping.
Air fry at 350F/180C for 15 minutes.
After the first 5 minutes flip the chips over.
Continue to air fry the chips, checking and flipping them every few minutes until they are done (remove any individual chips that are ready). They burn quite easily to reduce the temperature if need be.
Once done, sprinkle with additional pink salt, if needed.
Allow to cool and serve accordingly.