Pre-heat the oven to 350 degrees and line the baking sheet with parchment paper.
Cut the edges, peel, and slice the plantain thinly using a knife or mandolin. In a bowl, combine sliced plantains, salt, oil and mix well.
Arrange the sliced plantains in a single layer and bake in a pre-heated 350 degrees oven for 25 to 30 minutes until they start to brown the edges and turns crispy. Turn plantains to the other side after 10 minutes.