Butter a baking sheet and chill in the freezer until ready to pour candy.
Combine the sugar, salt and corn starch in a 3- to 4-quart saucepan. Add corn syrup, water, and glycerine; mix well. Place over medium heat and stir constantly until sugar is completely dissolved.
When syrup come to a boil, brush down the edges of the pan with a pastry brush dipped in water. It is important to remove all sugar crystals from the side of the pan or else they may cause the mixture to recrystallize later. Clip on candy thermometer and let boil undisturbed until the mixture reaches 265 degrees. DO NOT allow syrup to rise above 265 degrees, or else candy could turn out hard.
Remove from heat and add butter; stir well to combine. Allow to cool slightly, to approximately 240 degrees. Add flavorings and food coloring.
Pour out onto buttered baking sheet. As taffy begins to cool, lift edges towards the center. Continue to do so until taffy becomes cool enough to handle.
With buttered hands, stretch and pull taffy until it becomes opaque and is cooled to room temperature. Your goal with the stretching is to incorporate as much air as possible to yield a soft, chewy candy. When you see parallel ridges start to form, you are done pulling.
Take 1/5 of the candy and roll into a 1/2-inch rope; place on a buttered surface. Repeat for remaining candy. Using buttered scissors or knife, cut taffy into 1-inch pieces. Wrap in waxed paper and store in an airtight container. Makes approximately 1 pound.