Line a baking sheet with parchment paper or foil. Sift powdered sugar generously over the sheet.
In a heavy-bottomed saucepan, stir the sugar, corn syrup, and water over medium heat until the sugar dissolves.
Insert a candy thermometer into the saucepan and stop stirring. Bring to a light boil, without stirring, 15 minutes, or until it reaches 300°F or the hard crack stage. To check if it's done, drop a spoonful into ice cold water and it should harden.
Remove the saucepan from the heat and let cool 1 minute. Stir in the desired amount of flavor and food coloring 1 minute, or until combined.
Carefully pour the hot candy onto the lined baking sheet. Use a rubber spatula to spread it out evenly. Cool slightly, then sift powdered sugar over the top.
While still soft, use a large knife to score 1-inch squares across the candy (this will help it break easier). Let the candy cool and harden for at least 1 hour, or until it's completely set and at room temperature.
Once completely cooled and hardened, break into pieces. You can also use a hammer or mallet to break it into smaller shards, if desired.
Notes
Variations: If making more than 1 color or flavor, pour half the mixture into another pot and mix in the other color or flavor. You could also just make a second batch. Tip: To clean your pot, fill with hot water and bring to a light boil to remove the candy. Then clean immediately. Storage:Store your homemade hard candy in an airtight container between a layer of parchment paper at room temperature. It will stay fresh up to 1 month.