Step 1

Slice ginger very thin using a mandoline or sharp vegetable peeler. (It's OK if pieces vary in size.) Place ginger in a medium saucepan and add enough water to cover by about 2 inches. Bring to a boil over high heat; let boil for 5 minutes. Drain and rinse well with cold water. Return the ginger to the pan and cover with about 2 inches of water again; repeat the boiling, draining and rinsing two more times.

Step 2

Return the ginger to the pan. Add just enough water to cover the ginger, then add vinegar and maple syrup (or agave); bring the liquid to a boil. Boil, stirring occasionally, until there is about 1/2 inch of syrupy, thick liquid left in the bottom of the pan, 15 to 20 minutes. Let cool before serving.