As always we begin with sterilising out jars and getting our equipment ready. Thoroughly wash and rinse your jars and lids. Put the jars in a 120C (250F) oven. They will need to be kept above 100C for at least 10 minutes to make absolutely sure all the nasties are dead so do this first.

Put the lids in a heatproof bowl or jug and set aside. We will pour boiling water over these later. Lay out a folded tea towel next to the stove so you can put your hot jars there later. Put 2 or 3 small saucers or plates into the freezer to chill. We will use these to test if our jam is ready.

Roughly chop the feijoas and combine with the lime juice and lime zest in your pot or preserving pan. Zest your limes before juicing. It’s just easier.

Cook the fruit over a medium heat until it has broken down and become pulpy – about 15 minutes. You can encourage them to break down by smushing them with your wooden spoon or a vegetable masher.

Turn the heat right down and add the sugar.

Stir until all the sugar has dissolved. You will be able to hear and feel if there are sugar granules still floating around. It makes a scritchy sound on the bottom of the pot when you stir. When the sugar is dissolved turn the heat up to medium high and stop stirring. The jam should be at a boil. Adjust the temperature up or down to get a steady boil.

Use your thermometer to keep track of the temperature. I like to use the wrinkle test as my final test that the jam is ready but the thermometer lets you know when it’s getting close. Once it starts to show above 103C then start testing for a set. Also boil your jug.

To do this get one of your cold saucers out of the freezer. Drop a small spoonful of jam on it and pop it back in the freezer for a minute. Run your finger through the jam and see if it wrinkles up. If it does then the jam is ready.

You can double check that the temperature of the jam is 104.5C to 105C. Now get your jars out of the oven carefully and place them on the folded towel. Pour boiling water over your lids.

Using a ladle or a small pyrex jug carefully fill the jars leaving 3-5 mm of space at the top. Use a clean paper towel dipped in boiling water to clean any drips of the rim of the jars.

Drain the lids and seal the jars. Hold the jars with a towel so you can make sure the lids are on tight. Leave the jars to cool before labelling and storing.