Line a 9X13″ baking pan with parchment paper.
In a large pot, combine 2 ½ cups of sugar, corn syrup, and water. Stir over medium heat until sugar is dissolved.
Raise heat to medium-high and boil without stirring until the mixture reaches 300F/148C. Remove from heat and add red food coloring and cinnamon oil.
Quickly stir in baking soda and pour the foamy mixture into the prepared pan. Let it cool and solidify for at least an hour.
Once cool, break the candy into bite-sized chunks.
Melt black candy melts in a microwave-safe bowl. Prepare black sugar by kneading white sugar with black food coloring in a Ziplock bag.
Dip each piece of cinder toffee into the melted candy melt, then coat with black sugar. Place on parchment paper to cool.
