Spray a large baking sheet with non stick cooking spray and set aside.
In a large saucepan, stir together the sugar and corn starch. Using a wooden spoon, stir in the corn syrup, glycerin, butter, water and salt. Place saucepan over medium heat and stir continuously until the sugar has completely dissolved and mixture comes to a boil. Once mixture has come to a boil, allow to continue to cook, undisturbed, until it reaches 270° F on a candy thermometer. This is the soft-crack stage. (Make sure to wash down the sides of the saucepan with a pastry brush dipped in warm water while the syrup cooks. This will prevent any sugar crystals forming and clinging to the side of the pan, which could fall into the mixture and encourage recrystallization.)
Remove the saucepan from the heat. Very gently stir in the food coloring and vanilla. Pour mixture onto the prepared baking sheet and allow to cool just enough to handle.
Butter or spray your hands with a non stick cooking spray and begin to pull the taffy until it's light in color and has a satiny gloss. Have a friend help you with this step, and don't be concerned if the taffy doesn't seem to be "working". This step will take about 10 to 12 minutes.
Using the same baking tray, roll the pulled taffy into a long rope (about 1/2" diameter), and cut with a knife that has been sprayed with non stick cooking spray into 1" pieces. Allow to cool for 20 minutes before wrapping in wax paper.
Paula's note: Glycerin is a colorless liquid made from fats and oils. It can be found in most drugstores, some grocery stores and in craft stores in the cake decorating area. Using glycerin in this taffy recipe helps to make the candy soft and creamy.