Cut ginger into 2-inch pieces and slice lengthwise into 1/8-inch slices. Score ginger slices by pricking with a fork.

Toss ginger with sugar in a bowl.

Combine ginger-sugar mixture and water in a large skillet or wok; bring to a simmer. Reduce heat and cook, stirring occasionally, until sugar melts into a syrup and starts to crystallize, about 1 hour. Continue stirring until syrup is mostly crystallized and ginger comes together in a pile in the center of the skillet and very little syrup drains out; remove from heat.

Toss ginger slices gently to cool and separate from excess sugar. Spread slices out on a tray to cool and dry.