Combine zest, mint leaves and rum in a mason jar or other glass container.

Shake well to combine and leave to infuse in a cold dark place for about five days.

GIve glass a gentle shake or a stir once a day during the infusion period.

After five days, strain contents of jar into another vessel, making sure to squeeze every drop out of the mint.

Add sugar to your liking, making sure to taste as you do. Ideally you'll want something that's slightly sweet and palatable, still rum-like but not cloyingly sweet… But to each their own.

Pour back into original bottle or fancy bottle of choice, keep out of direct sunlight and consume at your own leisure.