With a small knife, make 3-4 cuts lengthwise down the plantain, just enough to go through the peel. Then remove the peel.
Thinly slice the plantain with a mandoline (on the thinnest setting). Add the plantain slices to a bowl and toss with the avocado oil to evenly coat.
Line a baking tray with parchment paper and place the plantain slices on the tray in one layer. Sprinkle with sea salt and bake for 15-20 minutes, or until just golden along the edges.
Notes
Be careful when using the mandoline as it is extremely sharp.