6 cups sugar
2 cups water
One 3-inch piece of fresh ginger, peeled and thinly sliced
1 1/2 cups fresh lime juice (from about 12 limes)
In a large saucepan, combine the sugar with the water and ginger and bring to a boil, stirring until the sugar is dissolved. Simmer over low heat, stirring occasionally, for 15 minutes longer. Stir in the lime juice and simmer until syrupy, about 15 minutes. Strain the syrup into jars and let cool completely before storing.