Before you start cutting, peel jicama with a vegetable peeler, then halve from top to bottom (a serrated knife works best). To julienne, slice jicama halves 1/8 inch thick; lay slices flat and cut into 1/8-inch-thick sticks.
Jicama's roots: Jicama is a mildly sweet and nutty root vegetable with a pleasant crunch. It's most often used raw. Look for the roots in the produce section, and choose those that feel solid and heavy.