Lightly grease your cookie sheets and insert craft sticks into the tops of the stemmed apples.
Combine sugar, water, and corn syrup in a medium saucepan and place over medium-high heat.
Bring the mixture to a boil, then carefully insert a candy thermometer into the syrup.
Continue boiling without stirring until the temperature reaches 300–310°F (149–154°C).
Test the syrup by dropping a small amount into cold water — it should form hard, brittle threads.
Remove the saucepan from heat and stir in the food coloring.
Hold each apple by its stick and dip it into the hot syrup, turning to coat it evenly.
Set each coated apple onto the prepared cookie sheet and let them harden completely.
