Place the whole grapefruit and the two oranges into a pot of boiling water for two minutes. Remove, run under cold water, and dry.

Cut the fruits into slices, remove the seeds and chop each slice into many pieces.

Place the small pieces and any juice that has resulted from the cutting process into the bottom of a large pan.

Peel and finely slice the carrots. Add to the pan.

Add the sugar.

Cover with a light kitchen towel and let sit for 6 hours.

Six hours later… bring the pot to a boil and then cook gently for approximately 20 minutes, stirring occasionally.

According to an old French proverb, the jam is ready when a drop on a cold plate does not spread. (Sounds so brilliantly simple and straight-forward and yet so ridden with uncertainties: how cold should the plate be? How big is a “drop”? What exactly qualifies as spreading? Best you ask your nearest Grand-mère.)

Once you are satisfied with your spreading drops or, like me, tired of waiting and wondering, add the pistachios. Let boil shortly.

Pour the jam into the jars. Close tightly and turn upside down to cool.