Plantains are tropical, starchy fruits that look like large bananas. They are firm when green and unripe, then soften as they turn yellow, and eventually, black. For the easiest peeling, cut off both ends of the plantain. Look at the ridges of the plantain. Cut a shallow slit down the length of each ridge (only cut as deep as the skin). Slide a butter knife down between the flesh and the skin, lifting up slightly to loosen it. The skin will come right off.