Peel the green bananas or green plantains; be careful as both tend to stain clothes and cutting boards. The plantains will be easier to peel, but the flesh of the green banana is more likely to stick to its skin.
Slice the bananas or plantains lengthwise, full length or half length, or slice them as thin rounds or thin diagonal ovals, use a mandolin to get that perfect thinness.
Heat the oil, either in a deep sauté pan or fryer, ideal temperature for frying these is between 375 F -400 F, there should be enough oil to fully cover the bananas or plantains.
Add the bananas or plantains to the hot oil; be careful not to overcrowd to keep them from sticking together.
Fry until the chips get a golden color.
Remove the chips from the oil and drain on paper towels.