Wash the apples thoroughly and dry them completely, since any moisture can keep the candy from sticking.

Remove the stems and insert a wooden stick firmly into the stem end of each apple, pushing it about halfway through.

Line a baking sheet with a silicone mat or parchment paper lightly sprayed with cooking spray.

In a medium, heavy saucepan, combine the sugar, corn syrup, and water. Cook over medium heat and stir gently only until the sugar dissolves. Then stop stirring completely.

Attach a candy thermometer to the side of the pan. Continue cooking without stirring until the syrup reaches 300 to 310 degrees F, which is the hard-crack stage.

Remove the pan from the heat as soon as it reaches temperature. Carefully stir in the red food coloring and flavoring oil, if using.

Working fast, tilt the saucepan and dip each apple into the syrup, turning it to coat all sides.

Let any extra syrup drip off for a few seconds, then place the apple stick-side up on the prepared baking sheet.

Let the apples cool at room temperature for 15 to 20 minutes until the shell is hard and glossy.

Serve them at room temperature for the best bite, and store any leftovers in a cool, dry place.