Butter a square 8x8x2 pan, and set aside. In a 2-quart sauce pan, combine the sugar, corn syrup, water, cornstarch, butter and salt. Cook over medium heat, stirring constantly, to 265 degrees on a candy thermometer (or until small amounts of the mixture dropped into very cold water forms a hard ball). Remove from the heat; stir in the vanilla and cayenne pepper, and pour into the greased pan.
When the taffy is just cool enough to handle, pull the taffy until it is satiny, light in color, and stiff. If the taffy becomes sticky, butter your hands lightly. Pull into long strips, 1/2 inch wide. Cut the strips into 1-inch pieces. Wrap the pieces individually in waxed paper, and store them in an airtight container.
