Cover the wok with a lid and leave it to cook on low-medium heat until the jicama softens to the texture you want.
I like mine soft on the outside and still crunchy inside.
Tip: Jicama varies in sweetness, so taste it here and adjust. If yours isn't very sweet, add a little sugar. If it needs more savouriness, add a splash more light soy sauce.
Add water when necessary so that the water doesn't dry out before the jicama turns soft.