Line a large rimmed baking tray with parchment. Spray a wire cooling rack with nonstick spray and position it over the parchment. Set aside.

Add sliced ginger to a medium saucepan. Cover with water and bring to a boil. Reduce heat to medium-low and simmer for 30 minutes.

Pass through a fine mesh sieve to drain the ginger, reserving the water.

Return boiled ginger to the saucepan, along with the sugar and 240 milliliters (1 cup) of the reserved cooking water. Bring to a boil. Reduce heat to medium-low and simmer, topping up with additional ginger water as needed, for 35-40 minutes or until ginger feels tender and most of the liquid evaporates.

Pass through a fine mesh strainer to drain.**

Arrange ginger pieces on prepared wire rack. Cool 2 hours or until slightly sticky, but not wet.

Toss in additional granulated sugar.

Line a large tray with parchment. Arrange coated ginger slices on tray and allow to sit, uncovered, at room temperature for 6-8 hours, or overnight. Use a metal spatula to flip the ginger halfway through the drying time.

Store candied ginger in an airtight container at room temperature for up to 1 month.