Wash mint well, then remove any stems or stalks. Roughly chop the mint leaves then add into a small saucepan with the water, which should just cover the leaves. Bring to a boil then simmer for two minutes, then turn the heat off and cover the pot, steep for about 10 minutes or until the liquid has cooled, while you heat the jars. Strain the liquid, squeezing any liquid from the leaves.

For each batch, you'll want to pre-heat your jars (I use half pint (125ml) or 4oz (75ml) jars) by covering in water and simmering for about 10 minutes. When we are ready to ladle the jelly into the jars, I heat the lids in the already hot water. The rings do not need to be heated. While the jars heat measure the remaining ingredients ready to use.

Measure the mint liquid into a large heavy-based pot, if there is not enough to make two cups, add enough water to the mint liquid to make two cups of liquid. Then whisk in the lime juice and powdered pectin. Bring to a boil over high heat, whisking every minute or so to distribute the pectin. Once it is at a high boil (bubbling and boiling lots), add the sugar all at once, whisking well. Bring to a rolling boil (will start to bubble and foam, cannot be stirred down), keeping at a rolling boil for 1 minute. Turn off the heat and stir through the white rum and green colouring (if using). Skim foam from surface and discard foam.

Ladle your hot jelly into hot half-pint jars (or whatever sized jar you want, I also did some small 4oz jars), leaving a ¼ inch (0.5cm) headspace. Wipe rims and seal immediately. Process in hot water bath canner for 10 minutes. Take lid off canner and rest jars in canner for 5 more minutes before removing to a tea towel covered surface to cool overnight.

The next day check for a seal - the jar lid should not flex up and down when pressed. Label sealed jars and store in a cool, dark, dry place for up to 12 months. Re-process any non-sealed jars or refrigerate for immediate use.