In a heavy (good quality) 2-quart saucepan, mix together sugar, corn syrup and water. Stir over medium heat until sugar dissolves. 

Insert candy thermometer if using, making certain it does not touch the bottom of the pan. Bring mixture to a boil without stirring. 

Early in the cooking process, "wash down" any sugar crystals that form on the sides of the pan with a wet pastry brush.

Continue to cook the syrup, without stirring, until the temperature reaches 126º C; add drops of colouring until desired hue is achieved. Do not stir; boiling action will incorporate colour into syrup.

Remove from heat precisely at 150° C (temperature will continue rising), or until drops of syrup form hard, brittle threads in cold water (hard crack stage). After boiling action has ceased, add flavour and stir. USE CAUTION WHEN ADDING FLAVOURING TO AVOID RISING STEAM. 

Carefully pour syrup into prepared moulds or onto the prepared greased and foil lined cookie sheet. (As the sugar mixture begins to set up, you may want to score with a large knife to mark squares.) Do not refrigerate. 

Cool completely. Break sheet candy into small pieces and dust with powdered sugar, if desired. Store in airtight containers between waxed paper. If making lollipops, do not dust with powdered sugar, but place in sucker bags and secure with twist ties. Store hard candy in a cool, dry place. Do not refrigerate.