This is a pleasant low-fat alternative to Rich Hot Lime Sauce. Use it in the same ways you would the richer sauce.
Combine in a small, heavy saucepan:
      1/2 cup sugar
      1 tablespoon cornstarch
Stir thoroughly, breaking up any lumps in the cornstarch. Stir in until well blended:
      1 cup water
      1/4 cup strained fresh lime juice
      Grated zest of 1 lime
      Pinch of salt
Stirring constantly with a heatproof rubber spatula or wooden spoon, bring the sauce to a boil and cook until thickened. Stir in, if you wish:
      1 to 2 tablespoons unsalted butter, cut into pieces
Serve the sauce at once, or let cool then cover and refrigerate for up to 1 week. Reheat over low heat, stirring.