In a small saucepan, combine the honey and red pepper flakes. Cook over medium heat just until the mixture begins to simmer. Be careful not to boil.

Remove the honey mixture from the heat and let it rest for 10 to 15 minutes. After the rest period, taste the honey. If you'd like more spice, let it rest for another 10 minutes or so.

When the honey has reached your desired spice level, place a fine mesh strainer over a medium jar. Pour the honey over the mesh strainer to remove the pepper flakes. If you'd like your honey to continue to get spicier, leave some or all of the red pepper flakes in the honey.

Stir in the apple cider vinegar.

Use the honey immediately or store at room temperature for up to 3 months.