Preheat the oven to 175 degrees, and lightly coat 2 cookie sheets with the oil.
Thinly slice the bananas (¼ inch thickness is ideal), and arrange them in a single layer on the cookie sheets.
Cook the bananas in the oven for about 3 hours, until they’re dehydrated but not rock solid.
Carefully remove the banana chips from the cookie sheets by gently peeling them off. Transfer them to a cooling rack, and let them cool completely before storing. These banana chips can be stored in an airtight container at room temperature for at least two weeks.