Cut the ginger into thin slices. Run a knife over it to chop it into rough, smaller pieces.
Place the ginger along with the water, sugar, and salt in a nonreactive saucepan. Heat to a boil, then reduce the heat to a steady simmer, and cook for 45 minutes to one hour.
Let cool, then strain the syrup through a fine-mesh strainer. Store the strained syrup in the refrigerator, covered, until ready to use. The syrup should keep for at least two weeks under refrigeration.
