Measure and add the honey and red pepper flakes into a small saucepan. Turn the heat on to medium and bring the mixture to a light simmer, stirring a few times throughout. Simmer it for 2 minutes while stirring, and turn off the heat.
Infuse:
Let the hot honey sit, with the heat turned off, for 10 to 15 minutes. The mixture will cool down as it sits. Taste test it after 10 minutes; the longer it sits, the more intense the heat.
Add the apple cider vinegar to the spicy honey and mix to combine.
Strain (optional):
Once the honey is spicy or mild enough for your liking, strain it through a fine mesh strainer into a jar. Otherwise, transfer it directly into a jar as is.
Storage:
Store the hot honey in a sealed jar in your pantry (indefinitely).
Notes
Using whole red chili peppers will yield a spicier honey. Simply chop 2 red chili peppers per cup of honey and omit the flakes from the recipe. Follow the rest of the steps.
You can omit the vinegar completely. The vinegar cuts down on the sweetness and lets the spice shine through, but you can't taste it.
Straining is optional. Once all the spicy oils are released into the honey, the pepper flakes will be there for decoration.