01 - Line a baking sheet with parchment paper. Core and wedge apples into six pieces each. Insert popsicle sticks or sturdy skewers into the base of each apple wedge. Lightly brush cut surfaces with lemon juice to prevent discoloration.
02 - Combine granulated sugar, light corn syrup, water, and cream of tartar in a heavy saucepan. Heat over medium heat, stirring constantly until sugar is fully dissolved.
03 - Bring mixture swiftly to a boil without additional stirring. Continue to cook until syrup registers 300°F (150°C) on a candy thermometer, reaching hard crack stage, typically in 8 to 10 minutes.
04 - Remove saucepan from heat immediately. Stir in desired food coloring and vanilla extract swiftly until evenly dispersed.
05 - Working quickly, immerse each apple wedge into hot candy syrup, ensuring a uniform coating. Allow excess to drip off and place coated slices on prepared parchment-lined baking sheet.
06 - If preferred, immediately garnish with mini chocolate chips, crushed nuts, or assorted sprinkles before candy coating hardens.
07 - Let coated apple slices cool and harden fully at room temperature prior to serving.