Trim off ends of plantains and cut 4 vertical slits in skin of each (do not cut into fruit). Microwave for 1 minute at 50 percent power, then pull off peel.
Cut diagonally into thin (scant 1/8-inch) slices.
Pour both oils into 3- to 4-inch-deep medium saucepan. Attach deep-fry thermometer to side of pan and heat oil to 350°F over medium heat. Working in batches, carefully add several plantain slices to hot oil. Cook until golden brown, turning occasionally, about 4 minutes. Using slotted spoon, transfer chips to paper towels to drain.
