Cut the ends from the plantains then score them along the seams. Peel away the skin. Slice diagonally and evenly into 1/2" pieces.
Over medium high heat, add oil to the skillet. When the oil is hot, add the plantains. Turn when they become golden brown. When both sides are golden, remove to a paper towel-lined plate.
In a non-stick pan, add the butter and sugar and mix until it starts to thicken, about 2-3 minutes. Add the plantains to the pan and cook for about 2-3 minutes or until they're brown on both sides.