Place an oven rack in the middle position. Preheat the oven to 350°F. Line 2 large baking sheets with parchment paper.

Trim one inch of the end off each plantain and then peel them. Slice each plantain, at a slight angle and as evenly as you can, into thin, about 1/8- to 1/4-inch thick slices. Place the slices in bowl. Add the oil and gently toss to coat.

Divide and set the slices of plantain in a single layer on the baking sheets. Sprinkle with sea salt. Bake the plantain, one sheet at a time, 25 minutes, or until golden and slightly crispy. Cool to room temperature, and then store in a tight-sealing container at room temperature until ready to enjoy.