Line a baking sheet with a silicone mat or parchment paper.
In a pot, bring the sugar, water and vinegar to a boil. When a candy thermometer reads 250°F (120°C), add the food coloring. Continue cooking until the thermometer reads 290°F (143°C). Remove from heat immediately.
Dip the apples, one at a time, in the syrup, tilting the pot as needed. Let excess syrup drip off the apple each a few seconds before placing on the baking sheet. If the syrup thickens, reheat the pot over low heat until it reaches the right consistency for dipping. The candy apples will keep for 2 to 3 days in an airtight container.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.