Do not, like me, get confused with the name of this candy. It's just a hard candy, not the rock candy that you make as a kid with a sugar solution and a stick.
Now that we're clear on that...
Rock Candy
From Mrs. Bourke's kitchen
2 cups sugar
1 cup water
3/4 cup corn syrup
1/2 teaspoon flavoring (use LorAnn candy oils, not regular extracts, which aren't strong enough)
food coloring
powdered sugar
Heat the sugar, water, and corn syrup in a saucepan over high heat. Heat until the mixture reaches 320*F, the hard crack stage. Mix in flavoring and food coloring quickly, then pour into a well oiled jelly roll pan. Allow to cool slightly, until it can be handled, but is still soft. Using a pair of clean scissors, cut the candy into manageable pieces, then cut into bite-sized pieces over a container of powdered sugar. Cool completely, then sift out of the powdered sugar. Store in an airtight container.
My Notes:
One of my friends has had this tradition in his family for years, where the whole family gets together one day and makes a ton of this rock candy. This year, my friend invited a bunch of people from school to help out. Total, we made 21 batches of this stuff, in various flavors, including spearmint, wintergreen, peppermint, cinnamon, licorice, and sassafras. It was a ton of fun, and afterwards, we had a fight with all the leftover powdered sugar.
Be warned, though, once the candy starts to harden, it doesn't really stop, so you have to work fast. Thus, it helps to have a ton of people around to help cut. Like this:
Yes, we did end up having fun with all that powdered sugar :)